Enter a problem...
Calculus Examples
limx→-∞√9x2-43x+5limx→−∞√9x2−43x+5
Step 1
Step 1.1
Rewrite 9x29x2 as (3x)2(3x)2.
limx→-∞√(3x)2-43x+5limx→−∞√(3x)2−43x+5
Step 1.2
Rewrite 44 as 2222.
limx→-∞√(3x)2-223x+5limx→−∞√(3x)2−223x+5
Step 1.3
Since both terms are perfect squares, factor using the difference of squares formula, a2-b2=(a+b)(a-b)a2−b2=(a+b)(a−b) where a=3xa=3x and b=2b=2.
limx→-∞√(3x+2)(3x-2)3x+5limx→−∞√(3x+2)(3x−2)3x+5
limx→-∞√(3x+2)(3x-2)3x+5limx→−∞√(3x+2)(3x−2)3x+5
Step 2
Divide the numerator and denominator by the highest power of xx in the denominator, which is -√x2=x−√x2=x.
limx→-∞-√(3x+2)(3x-2)x23xx+5xlimx→−∞−√(3x+2)(3x−2)x23xx+5x
Step 3
Step 3.1
Cancel the common factor of xx.
limx→-∞-√(3x+2)(3x-2)x23+5xlimx→−∞−√(3x+2)(3x−2)x23+5x
Step 3.2
Split the limit using the Limits Quotient Rule on the limit as xx approaches -∞−∞.
limx→-∞-√(3x+2)(3x-2)x2limx→-∞3+5xlimx→−∞−√(3x+2)(3x−2)x2limx→−∞3+5x
Step 3.3
Move the term -1 outside of the limit because it is constant with respect to x.
-limx→-∞√(3x+2)(3x-2)x2limx→-∞3+5x
Step 3.4
Move the limit under the radical sign.
-√limx→-∞(3x+2)(3x-2)x2limx→-∞3+5x
-√limx→-∞(3x+2)(3x-2)x2limx→-∞3+5x
Step 4
Step 4.1
Evaluate the limit of the numerator and the limit of the denominator.
Step 4.1.1
Take the limit of the numerator and the limit of the denominator.
-√limx→-∞(3x+2)(3x-2)limx→-∞x2limx→-∞3+5x
Step 4.1.2
Evaluate the limit of the numerator.
Step 4.1.2.1
Apply the distributive property.
-√limx→-∞3x(3x-2)+2(3x-2)limx→-∞x2limx→-∞3+5x
Step 4.1.2.2
Apply the distributive property.
-√limx→-∞3x⋅3x+3x⋅-2+2(3x-2)limx→-∞x2limx→-∞3+5x
Step 4.1.2.3
Apply the distributive property.
-√limx→-∞3x⋅3x+3x⋅-2+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.4
Simplify the expression.
Step 4.1.2.4.1
Move x.
-√limx→-∞3⋅3x⋅x+3x⋅-2+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.4.2
Move x.
-√limx→-∞3⋅3x⋅x+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.4.3
Multiply 3 by 3.
-√limx→-∞9x⋅x+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
-√limx→-∞9x⋅x+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.5
Raise x to the power of 1.
-√limx→-∞9x1x+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.6
Raise x to the power of 1.
-√limx→-∞9x1x1+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.7
Use the power rule aman=am+n to combine exponents.
-√limx→-∞9x1+1+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.8
Simplify by adding terms.
Step 4.1.2.8.1
Add 1 and 1.
-√limx→-∞9x2+3⋅-2x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.8.2
Multiply.
Step 4.1.2.8.2.1
Multiply 3 by -2.
-√limx→-∞9x2-6x+2⋅3x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.8.2.2
Multiply 2 by 3.
-√limx→-∞9x2-6x+6x+2⋅-2limx→-∞x2limx→-∞3+5x
Step 4.1.2.8.2.3
Multiply 2 by -2.
-√limx→-∞9x2-6x+6x-4limx→-∞x2limx→-∞3+5x
-√limx→-∞9x2-6x+6x-4limx→-∞x2limx→-∞3+5x
Step 4.1.2.8.3
Add -6x and 6x.
-√limx→-∞9x2+0-4limx→-∞x2limx→-∞3+5x
Step 4.1.2.8.4
Subtract 4 from 0.
-√limx→-∞9x2-4limx→-∞x2limx→-∞3+5x
-√limx→-∞9x2-4limx→-∞x2limx→-∞3+5x
Step 4.1.2.9
The limit at negative infinity of a polynomial of even degree whose leading coefficient is positive is infinity.
-√∞limx→-∞x2limx→-∞3+5x
-√∞limx→-∞x2limx→-∞3+5x
Step 4.1.3
The limit at negative infinity of a polynomial of even degree whose leading coefficient is positive is infinity.
-√∞∞limx→-∞3+5x
Step 4.1.4
Infinity divided by infinity is undefined.
Undefined
-√∞∞limx→-∞3+5x
Step 4.2
Since ∞∞ is of indeterminate form, apply L'Hospital's Rule. L'Hospital's Rule states that the limit of a quotient of functions is equal to the limit of the quotient of their derivatives.
limx→-∞(3x+2)(3x-2)x2=limx→-∞ddx[(3x+2)(3x-2)]ddx[x2]
Step 4.3
Find the derivative of the numerator and denominator.
Step 4.3.1
Differentiate the numerator and denominator.
-√limx→-∞ddx[(3x+2)(3x-2)]ddx[x2]limx→-∞3+5x
Step 4.3.2
Differentiate using the Product Rule which states that ddx[f(x)g(x)] is f(x)ddx[g(x)]+g(x)ddx[f(x)] where f(x)=3x+2 and g(x)=3x-2.
-√limx→-∞(3x+2)ddx[3x-2]+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.3
By the Sum Rule, the derivative of 3x-2 with respect to x is ddx[3x]+ddx[-2].
-√limx→-∞(3x+2)(ddx[3x]+ddx[-2])+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.4
Since 3 is constant with respect to x, the derivative of 3x with respect to x is 3ddx[x].
-√limx→-∞(3x+2)(3ddx[x]+ddx[-2])+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.5
Differentiate using the Power Rule which states that ddx[xn] is nxn-1 where n=1.
-√limx→-∞(3x+2)(3⋅1+ddx[-2])+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.6
Multiply 3 by 1.
-√limx→-∞(3x+2)(3+ddx[-2])+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.7
Since -2 is constant with respect to x, the derivative of -2 with respect to x is 0.
-√limx→-∞(3x+2)(3+0)+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.8
Add 3 and 0.
-√limx→-∞(3x+2)⋅3+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.9
Move 3 to the left of 3x+2.
-√limx→-∞3⋅(3x+2)+(3x-2)ddx[3x+2]ddx[x2]limx→-∞3+5x
Step 4.3.10
By the Sum Rule, the derivative of 3x+2 with respect to x is ddx[3x]+ddx[2].
-√limx→-∞3(3x+2)+(3x-2)(ddx[3x]+ddx[2])ddx[x2]limx→-∞3+5x
Step 4.3.11
Since 3 is constant with respect to x, the derivative of 3x with respect to x is 3ddx[x].
-√limx→-∞3(3x+2)+(3x-2)(3ddx[x]+ddx[2])ddx[x2]limx→-∞3+5x
Step 4.3.12
Differentiate using the Power Rule which states that ddx[xn] is nxn-1 where n=1.
-√limx→-∞3(3x+2)+(3x-2)(3⋅1+ddx[2])ddx[x2]limx→-∞3+5x
Step 4.3.13
Multiply 3 by 1.
-√limx→-∞3(3x+2)+(3x-2)(3+ddx[2])ddx[x2]limx→-∞3+5x
Step 4.3.14
Since 2 is constant with respect to x, the derivative of 2 with respect to x is 0.
-√limx→-∞3(3x+2)+(3x-2)(3+0)ddx[x2]limx→-∞3+5x
Step 4.3.15
Add 3 and 0.
-√limx→-∞3(3x+2)+(3x-2)⋅3ddx[x2]limx→-∞3+5x
Step 4.3.16
Move 3 to the left of 3x-2.
-√limx→-∞3(3x+2)+3⋅(3x-2)ddx[x2]limx→-∞3+5x
Step 4.3.17
Simplify.
Step 4.3.17.1
Apply the distributive property.
-√limx→-∞3⋅3x+3⋅2+3(3x-2)ddx[x2]limx→-∞3+5x
Step 4.3.17.2
Apply the distributive property.
-√limx→-∞3⋅3x+3⋅2+3⋅3x+3⋅-2ddx[x2]limx→-∞3+5x
Step 4.3.17.3
Combine terms.
Step 4.3.17.3.1
Multiply 3 by 3.
-√limx→-∞9x+3⋅2+3⋅3x+3⋅-2ddx[x2]limx→-∞3+5x
Step 4.3.17.3.2
Multiply 3 by 2.
-√limx→-∞9x+6+3⋅3x+3⋅-2ddx[x2]limx→-∞3+5x
Step 4.3.17.3.3
Multiply 3 by 3.
-√limx→-∞9x+6+9x+3⋅-2ddx[x2]limx→-∞3+5x
Step 4.3.17.3.4
Multiply 3 by -2.
-√limx→-∞9x+6+9x-6ddx[x2]limx→-∞3+5x
Step 4.3.17.3.5
Add 9x and 9x.
-√limx→-∞18x+6-6ddx[x2]limx→-∞3+5x
Step 4.3.17.3.6
Subtract 6 from 6.
-√limx→-∞18x+0ddx[x2]limx→-∞3+5x
Step 4.3.17.3.7
Add 18x and 0.
-√limx→-∞18xddx[x2]limx→-∞3+5x
-√limx→-∞18xddx[x2]limx→-∞3+5x
-√limx→-∞18xddx[x2]limx→-∞3+5x
Step 4.3.18
Differentiate using the Power Rule which states that ddx[xn] is nxn-1 where n=2.
-√limx→-∞18x2xlimx→-∞3+5x
-√limx→-∞18x2xlimx→-∞3+5x
Step 4.4
Reduce.
Step 4.4.1
Cancel the common factor of 18 and 2.
Step 4.4.1.1
Factor 2 out of 18x.
-√limx→-∞2⋅9x2xlimx→-∞3+5x
Step 4.4.1.2
Cancel the common factors.
Step 4.4.1.2.1
Factor 2 out of 2x.
-√limx→-∞2⋅9x2(x)limx→-∞3+5x
Step 4.4.1.2.2
Cancel the common factor.
-√limx→-∞2⋅9x2xlimx→-∞3+5x
Step 4.4.1.2.3
Rewrite the expression.
-√limx→-∞9xxlimx→-∞3+5x
-√limx→-∞9xxlimx→-∞3+5x
-√limx→-∞9xxlimx→-∞3+5x
Step 4.4.2
Cancel the common factor of x.
Step 4.4.2.1
Cancel the common factor.
-√limx→-∞9xxlimx→-∞3+5x
Step 4.4.2.2
Divide 9 by 1.
-√limx→-∞9limx→-∞3+5x
-√limx→-∞9limx→-∞3+5x
-√limx→-∞9limx→-∞3+5x
-√limx→-∞9limx→-∞3+5x
Step 5
Step 5.1
Evaluate the limit of 9 which is constant as x approaches -∞.
-√9limx→-∞3+5x
Step 5.2
Split the limit using the Sum of Limits Rule on the limit as x approaches -∞.
-√9limx→-∞3+limx→-∞5x
Step 5.3
Evaluate the limit of 3 which is constant as x approaches -∞.
-√93+limx→-∞5x
Step 5.4
Move the term 5 outside of the limit because it is constant with respect to x.
-√93+5limx→-∞1x
-√93+5limx→-∞1x
Step 6
Since its numerator approaches a real number while its denominator is unbounded, the fraction 1x approaches 0.
-√93+5⋅0
Step 7
Step 7.1
Simplify the numerator.
Step 7.1.1
Rewrite 9 as 32.
-√323+5⋅0
Step 7.1.2
Pull terms out from under the radical, assuming positive real numbers.
-1⋅33+5⋅0
-1⋅33+5⋅0
Step 7.2
Simplify the denominator.
Step 7.2.1
Multiply 5 by 0.
-1⋅33+0
Step 7.2.2
Add 3 and 0.
-1⋅33
-1⋅33
Step 7.3
Multiply -1 by 3.
-33
Step 7.4
Divide -3 by 3.
-1
-1