Algebra Examples

Solve by Completing the Square x^2-7x+10=0
x2-7x+10=0
Step 1
Subtract 10 from both sides of the equation.
x2-7x=-10
Step 2
To create a trinomial square on the left side of the equation, find a value that is equal to the square of half of b.
(b2)2=(-72)2
Step 3
Add the term to each side of the equation.
x2-7x+(-72)2=-10+(-72)2
Step 4
Simplify the equation.
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Step 4.1
Simplify the left side.
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Step 4.1.1
Simplify each term.
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Step 4.1.1.1
Use the power rule (ab)n=anbn to distribute the exponent.
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Step 4.1.1.1.1
Apply the product rule to -72.
x2-7x+(-1)2(72)2=-10+(-72)2
Step 4.1.1.1.2
Apply the product rule to 72.
x2-7x+(-1)27222=-10+(-72)2
x2-7x+(-1)27222=-10+(-72)2
Step 4.1.1.2
Raise -1 to the power of 2.
x2-7x+17222=-10+(-72)2
Step 4.1.1.3
Multiply 7222 by 1.
x2-7x+7222=-10+(-72)2
Step 4.1.1.4
Raise 7 to the power of 2.
x2-7x+4922=-10+(-72)2
Step 4.1.1.5
Raise 2 to the power of 2.
x2-7x+494=-10+(-72)2
x2-7x+494=-10+(-72)2
x2-7x+494=-10+(-72)2
Step 4.2
Simplify the right side.
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Step 4.2.1
Simplify -10+(-72)2.
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Step 4.2.1.1
Simplify each term.
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Step 4.2.1.1.1
Use the power rule (ab)n=anbn to distribute the exponent.
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Step 4.2.1.1.1.1
Apply the product rule to -72.
x2-7x+494=-10+(-1)2(72)2
Step 4.2.1.1.1.2
Apply the product rule to 72.
x2-7x+494=-10+(-1)27222
x2-7x+494=-10+(-1)27222
Step 4.2.1.1.2
Raise -1 to the power of 2.
x2-7x+494=-10+17222
Step 4.2.1.1.3
Multiply 7222 by 1.
x2-7x+494=-10+7222
Step 4.2.1.1.4
Raise 7 to the power of 2.
x2-7x+494=-10+4922
Step 4.2.1.1.5
Raise 2 to the power of 2.
x2-7x+494=-10+494
x2-7x+494=-10+494
Step 4.2.1.2
To write -10 as a fraction with a common denominator, multiply by 44.
x2-7x+494=-1044+494
Step 4.2.1.3
Combine -10 and 44.
x2-7x+494=-1044+494
Step 4.2.1.4
Combine the numerators over the common denominator.
x2-7x+494=-104+494
Step 4.2.1.5
Simplify the numerator.
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Step 4.2.1.5.1
Multiply -10 by 4.
x2-7x+494=-40+494
Step 4.2.1.5.2
Add -40 and 49.
x2-7x+494=94
x2-7x+494=94
x2-7x+494=94
x2-7x+494=94
x2-7x+494=94
Step 5
Factor the perfect trinomial square into (x-72)2.
(x-72)2=94
Step 6
Solve the equation for x.
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Step 6.1
Take the specified root of both sides of the equation to eliminate the exponent on the left side.
x-72=±94
Step 6.2
Simplify ±94.
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Step 6.2.1
Rewrite 94 as 94.
x-72=±94
Step 6.2.2
Simplify the numerator.
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Step 6.2.2.1
Rewrite 9 as 32.
x-72=±324
Step 6.2.2.2
Pull terms out from under the radical, assuming positive real numbers.
x-72=±34
x-72=±34
Step 6.2.3
Simplify the denominator.
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Step 6.2.3.1
Rewrite 4 as 22.
x-72=±322
Step 6.2.3.2
Pull terms out from under the radical, assuming positive real numbers.
x-72=±32
x-72=±32
x-72=±32
Step 6.3
The complete solution is the result of both the positive and negative portions of the solution.
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Step 6.3.1
First, use the positive value of the ± to find the first solution.
x-72=32
Step 6.3.2
Move all terms not containing x to the right side of the equation.
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Step 6.3.2.1
Add 72 to both sides of the equation.
x=32+72
Step 6.3.2.2
Combine the numerators over the common denominator.
x=3+72
Step 6.3.2.3
Add 3 and 7.
x=102
Step 6.3.2.4
Divide 10 by 2.
x=5
x=5
Step 6.3.3
Next, use the negative value of the ± to find the second solution.
x-72=-32
Step 6.3.4
Move all terms not containing x to the right side of the equation.
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Step 6.3.4.1
Add 72 to both sides of the equation.
x=-32+72
Step 6.3.4.2
Combine the numerators over the common denominator.
x=-3+72
Step 6.3.4.3
Add -3 and 7.
x=42
Step 6.3.4.4
Divide 4 by 2.
x=2
x=2
Step 6.3.5
The complete solution is the result of both the positive and negative portions of the solution.
x=5,2
x=5,2
x=5,2
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