When solving $x^2 – 4x = –7$ by completing the square what value is added to both sides of the equation?

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Answer 1 · 2015-04-29T11:47:04

Your question is equivalent to asking:
What value needs to be added to $x^2-4x$
to make the expression a square of the form
$(x+a)^2 = x^2+2ax +a^2$

We have $2ax = -4x$
$rarr a=-2$

So $a^2 = 4$

We need to add $4$ to $x^2-4x$ in order to complete the square.

When solving x^2 – 4x = –7x^2 – 4x = –7 by completing the square what value is added to both sides of the equation?