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34 votes
34 votes
What number should be added to both sides of the equation to complete the squa
x2 - 10x = 7

User Diogo Sgrillo
by
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1 Answer

27 votes
27 votes

Given:

The equation is:


x^2-10x=7

To find:

The number that should be added to sides of the equation to complete the square.

Solution:

If an expression is in the form of
x^2+bx, then we have to add
\left((b)/(2)\right)^2 to make it perfect square.

We have,


x^2-10x=7 ...(i)

To make it perfect square we need to add square of half of coefficient of x on both sides.

Coefficient of x is -10, so square of half of coefficient of x is:


\left((-10)/(2)\right)^2=(-5)^2


\left((-10)/(2)\right)^2=25

On adding 25 on both sides of (i), we get


x^2-10x+25=7+25


(x-5)^2=32

Therefore, we need to add 25 to both sides of the equation to complete the square.

User Jetti Madhu
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2.8k points