Calculus Examples

Find the Absolute Max and Min over the Interval g(x)=1/12x^2-9 square root of x on 0 , 16
g(x)=112x2-9xg(x)=112x29x on 00 , 1616
Step 1
Find the critical points.
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Step 1.1
Find the first derivative.
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Step 1.1.1
Find the first derivative.
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Step 1.1.1.1
By the Sum Rule, the derivative of 112x2-9x112x29x with respect to xx is ddx[112x2]+ddx[-9x]ddx[112x2]+ddx[9x].
ddx[112x2]+ddx[-9x]ddx[112x2]+ddx[9x]
Step 1.1.1.2
Evaluate ddx[112x2]ddx[112x2].
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Step 1.1.1.2.1
Since 112112 is constant with respect to xx, the derivative of 112x2112x2 with respect to xx is 112ddx[x2]112ddx[x2].
112ddx[x2]+ddx[-9x]112ddx[x2]+ddx[9x]
Step 1.1.1.2.2
Differentiate using the Power Rule which states that ddx[xn]ddx[xn] is nxn-1nxn1 where n=2n=2.
112(2x)+ddx[-9x]112(2x)+ddx[9x]
Step 1.1.1.2.3
Combine 22 and 112112.
212x+ddx[-9x]212x+ddx[9x]
Step 1.1.1.2.4
Combine 212212 and xx.
2x12+ddx[-9x]2x12+ddx[9x]
Step 1.1.1.2.5
Cancel the common factor of 22 and 1212.
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Step 1.1.1.2.5.1
Factor 22 out of 2x2x.
2(x)12+ddx[-9x]2(x)12+ddx[9x]
Step 1.1.1.2.5.2
Cancel the common factors.
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Step 1.1.1.2.5.2.1
Factor 22 out of 1212.
2x26+ddx[-9x]2x26+ddx[9x]
Step 1.1.1.2.5.2.2
Cancel the common factor.
2x26+ddx[-9x]
Step 1.1.1.2.5.2.3
Rewrite the expression.
x6+ddx[-9x]
x6+ddx[-9x]
x6+ddx[-9x]
x6+ddx[-9x]
Step 1.1.1.3
Evaluate ddx[-9x].
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Step 1.1.1.3.1
Use nax=axn to rewrite x as x12.
x6+ddx[-9x12]
Step 1.1.1.3.2
Since -9 is constant with respect to x, the derivative of -9x12 with respect to x is -9ddx[x12].
x6-9ddx[x12]
Step 1.1.1.3.3
Differentiate using the Power Rule which states that ddx[xn] is nxn-1 where n=12.
x6-9(12x12-1)
Step 1.1.1.3.4
To write -1 as a fraction with a common denominator, multiply by 22.
x6-9(12x12-122)
Step 1.1.1.3.5
Combine -1 and 22.
x6-9(12x12+-122)
Step 1.1.1.3.6
Combine the numerators over the common denominator.
x6-9(12x1-122)
Step 1.1.1.3.7
Simplify the numerator.
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Step 1.1.1.3.7.1
Multiply -1 by 2.
x6-9(12x1-22)
Step 1.1.1.3.7.2
Subtract 2 from 1.
x6-9(12x-12)
x6-9(12x-12)
Step 1.1.1.3.8
Move the negative in front of the fraction.
x6-9(12x-12)
Step 1.1.1.3.9
Combine 12 and x-12.
x6-9x-122
Step 1.1.1.3.10
Combine -9 and x-122.
x6+-9x-122
Step 1.1.1.3.11
Move x-12 to the denominator using the negative exponent rule b-n=1bn.
x6+-92x12
Step 1.1.1.3.12
Move the negative in front of the fraction.
f(x)=x6-92x12
f(x)=x6-92x12
f(x)=x6-92x12
Step 1.1.2
The first derivative of g(x) with respect to x is x6-92x12.
x6-92x12
x6-92x12
Step 1.2
Set the first derivative equal to 0 then solve the equation x6-92x12=0.
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Step 1.2.1
Set the first derivative equal to 0.
x6-92x12=0
Step 1.2.2
Find the LCD of the terms in the equation.
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Step 1.2.2.1
Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.
6,2x12,1
Step 1.2.2.2
Since 6,2x12,1 contains both numbers and variables, there are two steps to find the LCM. Find LCM for the numeric part 6,2,1 then find LCM for the variable part x12.
Step 1.2.2.3
The LCM is the smallest positive number that all of the numbers divide into evenly.
1. List the prime factors of each number.
2. Multiply each factor the greatest number of times it occurs in either number.
Step 1.2.2.4
6 has factors of 2 and 3.
23
Step 1.2.2.5
Since 2 has no factors besides 1 and 2.
2 is a prime number
Step 1.2.2.6
The number 1 is not a prime number because it only has one positive factor, which is itself.
Not prime
Step 1.2.2.7
The LCM of 6,2,1 is the result of multiplying all prime factors the greatest number of times they occur in either number.
23
Step 1.2.2.8
Multiply 2 by 3.
6
Step 1.2.2.9
The LCM of x12 is the result of multiplying all prime factors the greatest number of times they occur in either term.
x12
Step 1.2.2.10
The LCM for 6,2x12,1 is the numeric part 6 multiplied by the variable part.
6x12
6x12
Step 1.2.3
Multiply each term in x6-92x12=0 by 6x12 to eliminate the fractions.
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Step 1.2.3.1
Multiply each term in x6-92x12=0 by 6x12.
x6(6x12)-92x12(6x12)=0(6x12)
Step 1.2.3.2
Simplify the left side.
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Step 1.2.3.2.1
Simplify each term.
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Step 1.2.3.2.1.1
Rewrite using the commutative property of multiplication.
6x6x12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.2
Cancel the common factor of 6.
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Step 1.2.3.2.1.2.1
Cancel the common factor.
6x6x12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.2.2
Rewrite the expression.
xx12-92x12(6x12)=0(6x12)
xx12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.3
Multiply x by x12 by adding the exponents.
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Step 1.2.3.2.1.3.1
Multiply x by x12.
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Step 1.2.3.2.1.3.1.1
Raise x to the power of 1.
x1x12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.3.1.2
Use the power rule aman=am+n to combine exponents.
x1+12-92x12(6x12)=0(6x12)
x1+12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.3.2
Write 1 as a fraction with a common denominator.
x22+12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.3.3
Combine the numerators over the common denominator.
x2+12-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.3.4
Add 2 and 1.
x32-92x12(6x12)=0(6x12)
x32-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.4
Cancel the common factor of 2x12.
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Step 1.2.3.2.1.4.1
Move the leading negative in -92x12 into the numerator.
x32+-92x12(6x12)=0(6x12)
Step 1.2.3.2.1.4.2
Factor 2x12 out of 6x12.
x32+-92x12(2x12(3))=0(6x12)
Step 1.2.3.2.1.4.3
Cancel the common factor.
x32+-92x12(2x123)=0(6x12)
Step 1.2.3.2.1.4.4
Rewrite the expression.
x32-93=0(6x12)
x32-93=0(6x12)
Step 1.2.3.2.1.5
Multiply -9 by 3.
x32-27=0(6x12)
x32-27=0(6x12)
x32-27=0(6x12)
Step 1.2.3.3
Simplify the right side.
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Step 1.2.3.3.1
Multiply 0(6x12).
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Step 1.2.3.3.1.1
Multiply 6 by 0.
x32-27=0x12
Step 1.2.3.3.1.2
Multiply 0 by x12.
x32-27=0
x32-27=0
x32-27=0
x32-27=0
Step 1.2.4
Solve the equation.
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Step 1.2.4.1
Add 27 to both sides of the equation.
x32=27
Step 1.2.4.2
Raise each side of the equation to the power of 23 to eliminate the fractional exponent on the left side.
(x32)23=2723
Step 1.2.4.3
Simplify the exponent.
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Step 1.2.4.3.1
Simplify the left side.
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Step 1.2.4.3.1.1
Simplify (x32)23.
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Step 1.2.4.3.1.1.1
Multiply the exponents in (x32)23.
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Step 1.2.4.3.1.1.1.1
Apply the power rule and multiply exponents, (am)n=amn.
x3223=2723
Step 1.2.4.3.1.1.1.2
Cancel the common factor of 3.
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Step 1.2.4.3.1.1.1.2.1
Cancel the common factor.
x3223=2723
Step 1.2.4.3.1.1.1.2.2
Rewrite the expression.
x122=2723
x122=2723
Step 1.2.4.3.1.1.1.3
Cancel the common factor of 2.
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Step 1.2.4.3.1.1.1.3.1
Cancel the common factor.
x122=2723
Step 1.2.4.3.1.1.1.3.2
Rewrite the expression.
x1=2723
x1=2723
x1=2723
Step 1.2.4.3.1.1.2
Simplify.
x=2723
x=2723
x=2723
Step 1.2.4.3.2
Simplify the right side.
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Step 1.2.4.3.2.1
Simplify 2723.
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Step 1.2.4.3.2.1.1
Simplify the expression.
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Step 1.2.4.3.2.1.1.1
Rewrite 27 as 33.
x=(33)23
Step 1.2.4.3.2.1.1.2
Apply the power rule and multiply exponents, (am)n=amn.
x=33(23)
x=33(23)
Step 1.2.4.3.2.1.2
Cancel the common factor of 3.
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Step 1.2.4.3.2.1.2.1
Cancel the common factor.
x=33(23)
Step 1.2.4.3.2.1.2.2
Rewrite the expression.
x=32
x=32
Step 1.2.4.3.2.1.3
Raise 3 to the power of 2.
x=9
x=9
x=9
x=9
x=9
x=9
Step 1.3
Find the values where the derivative is undefined.
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Step 1.3.1
Convert expressions with fractional exponents to radicals.
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Step 1.3.1.1
Apply the rule xmn=nxm to rewrite the exponentiation as a radical.
x6-92x1
Step 1.3.1.2
Anything raised to 1 is the base itself.
x6-92x
x6-92x
Step 1.3.2
Set the denominator in 92x equal to 0 to find where the expression is undefined.
2x=0
Step 1.3.3
Solve for x.
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Step 1.3.3.1
To remove the radical on the left side of the equation, square both sides of the equation.
(2x)2=02
Step 1.3.3.2
Simplify each side of the equation.
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Step 1.3.3.2.1
Use nax=axn to rewrite x as x12.
(2x12)2=02
Step 1.3.3.2.2
Simplify the left side.
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Step 1.3.3.2.2.1
Simplify (2x12)2.
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Step 1.3.3.2.2.1.1
Apply the product rule to 2x12.
22(x12)2=02
Step 1.3.3.2.2.1.2
Raise 2 to the power of 2.
4(x12)2=02
Step 1.3.3.2.2.1.3
Multiply the exponents in (x12)2.
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Step 1.3.3.2.2.1.3.1
Apply the power rule and multiply exponents, (am)n=amn.
4x122=02
Step 1.3.3.2.2.1.3.2
Cancel the common factor of 2.
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Step 1.3.3.2.2.1.3.2.1
Cancel the common factor.
4x122=02
Step 1.3.3.2.2.1.3.2.2
Rewrite the expression.
4x1=02
4x1=02
4x1=02
Step 1.3.3.2.2.1.4
Simplify.
4x=02
4x=02
4x=02
Step 1.3.3.2.3
Simplify the right side.
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Step 1.3.3.2.3.1
Raising 0 to any positive power yields 0.
4x=0
4x=0
4x=0
Step 1.3.3.3
Divide each term in 4x=0 by 4 and simplify.
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Step 1.3.3.3.1
Divide each term in 4x=0 by 4.
4x4=04
Step 1.3.3.3.2
Simplify the left side.
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Step 1.3.3.3.2.1
Cancel the common factor of 4.
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Step 1.3.3.3.2.1.1
Cancel the common factor.
4x4=04
Step 1.3.3.3.2.1.2
Divide x by 1.
x=04
x=04
x=04
Step 1.3.3.3.3
Simplify the right side.
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Step 1.3.3.3.3.1
Divide 0 by 4.
x=0
x=0
x=0
x=0
Step 1.3.4
Set the radicand in x less than 0 to find where the expression is undefined.
x<0
Step 1.3.5
The equation is undefined where the denominator equals 0, the argument of a square root is less than 0, or the argument of a logarithm is less than or equal to 0.
x0
(-,0]
x0
(-,0]
Step 1.4
Evaluate 112x2-9x at each x value where the derivative is 0 or undefined.
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Step 1.4.1
Evaluate at x=9.
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Step 1.4.1.1
Substitute 9 for x.
112(9)2-99
Step 1.4.1.2
Simplify.
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Step 1.4.1.2.1
Simplify each term.
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Step 1.4.1.2.1.1
Raise 9 to the power of 2.
11281-99
Step 1.4.1.2.1.2
Cancel the common factor of 3.
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Step 1.4.1.2.1.2.1
Factor 3 out of 12.
13(4)81-99
Step 1.4.1.2.1.2.2
Factor 3 out of 81.
134(327)-99
Step 1.4.1.2.1.2.3
Cancel the common factor.
134(327)-99
Step 1.4.1.2.1.2.4
Rewrite the expression.
1427-99
1427-99
Step 1.4.1.2.1.3
Combine 14 and 27.
274-99
Step 1.4.1.2.1.4
Rewrite 9 as 32.
274-932
Step 1.4.1.2.1.5
Pull terms out from under the radical, assuming positive real numbers.
274-93
Step 1.4.1.2.1.6
Multiply -9 by 3.
274-27
274-27
Step 1.4.1.2.2
To write -27 as a fraction with a common denominator, multiply by 44.
274-2744
Step 1.4.1.2.3
Combine -27 and 44.
274+-2744
Step 1.4.1.2.4
Combine the numerators over the common denominator.
27-2744
Step 1.4.1.2.5
Simplify the numerator.
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Step 1.4.1.2.5.1
Multiply -27 by 4.
27-1084
Step 1.4.1.2.5.2
Subtract 108 from 27.
-814
-814
Step 1.4.1.2.6
Move the negative in front of the fraction.
-814
-814
-814
Step 1.4.2
Evaluate at x=0.
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Step 1.4.2.1
Substitute 0 for x.
112(0)2-90
Step 1.4.2.2
Simplify.
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Step 1.4.2.2.1
Simplify each term.
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Step 1.4.2.2.1.1
Raising 0 to any positive power yields 0.
1120-90
Step 1.4.2.2.1.2
Multiply 112 by 0.
0-90
Step 1.4.2.2.1.3
Rewrite 0 as 02.
0-902
Step 1.4.2.2.1.4
Pull terms out from under the radical, assuming positive real numbers.
0-90
Step 1.4.2.2.1.5
Multiply -9 by 0.
0+0
0+0
Step 1.4.2.2.2
Add 0 and 0.
0
0
0
Step 1.4.3
List all of the points.
(9,-814),(0,0)
(9,-814),(0,0)
(9,-814),(0,0)
Step 2
Evaluate at the included endpoints.
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Step 2.1
Evaluate at x=0.
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Step 2.1.1
Substitute 0 for x.
112(0)2-90
Step 2.1.2
Simplify.
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Step 2.1.2.1
Simplify each term.
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Step 2.1.2.1.1
Raising 0 to any positive power yields 0.
1120-90
Step 2.1.2.1.2
Multiply 112 by 0.
0-90
Step 2.1.2.1.3
Rewrite 0 as 02.
0-902
Step 2.1.2.1.4
Pull terms out from under the radical, assuming positive real numbers.
0-90
Step 2.1.2.1.5
Multiply -9 by 0.
0+0
0+0
Step 2.1.2.2
Add 0 and 0.
0
0
0
Step 2.2
Evaluate at x=16.
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Step 2.2.1
Substitute 16 for x.
112(16)2-916
Step 2.2.2
Simplify.
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Step 2.2.2.1
Simplify each term.
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Step 2.2.2.1.1
Raise 16 to the power of 2.
112256-916
Step 2.2.2.1.2
Cancel the common factor of 4.
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Step 2.2.2.1.2.1
Factor 4 out of 12.
14(3)256-916
Step 2.2.2.1.2.2
Factor 4 out of 256.
143(464)-916
Step 2.2.2.1.2.3
Cancel the common factor.
143(464)-916
Step 2.2.2.1.2.4
Rewrite the expression.
1364-916
1364-916
Step 2.2.2.1.3
Combine 13 and 64.
643-916
Step 2.2.2.1.4
Rewrite 16 as 42.
643-942
Step 2.2.2.1.5
Pull terms out from under the radical, assuming positive real numbers.
643-94
Step 2.2.2.1.6
Multiply -9 by 4.
643-36
643-36
Step 2.2.2.2
To write -36 as a fraction with a common denominator, multiply by 33.
643-3633
Step 2.2.2.3
Combine -36 and 33.
643+-3633
Step 2.2.2.4
Combine the numerators over the common denominator.
64-3633
Step 2.2.2.5
Simplify the numerator.
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Step 2.2.2.5.1
Multiply -36 by 3.
64-1083
Step 2.2.2.5.2
Subtract 108 from 64.
-443
-443
Step 2.2.2.6
Move the negative in front of the fraction.
-443
-443
-443
Step 2.3
List all of the points.
(0,0),(16,-443)
(0,0),(16,-443)
Step 3
Compare the g(x) values found for each value of x in order to determine the absolute maximum and minimum over the given interval. The maximum will occur at the highest g(x) value and the minimum will occur at the lowest g(x) value.
Absolute Maximum: (0,0)
Absolute Minimum: (9,-814)
Step 4
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