How do you solve $x^2 - 4x = -3$ by completing the square?

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Answer 1 · 2017-10-11T00:20:00

$x=3$ OR $x=1$

We want to add a number on both sides of the equation so that the left side becomes a perfect square:

To do that, we look at $b$ (the number next to $x$ ) and see that it is $-4$

If you add $(b/2)^2$ to both sides, the equation on the left will be a perfect square or:

$(-4/2)^2=(-2)^2=4$

So:

$x^2-4xcolor(red)(+4)=-3color(red)(+4)$

$(x-2)^2=1$

$sqrt((x-2)^2)=sqrt(1)$

$x-2=1$ OR $x-2=-1$

$x=3$ OR $x=1$

How do you solve x^2 - 4x = -3x^2 - 4x = -3 by completing the square?