How do you solve by completing the square $x^2+8x-9=0$ ?

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Answer 1 · 2015-03-31T00:40:25

The quadratic that is a square and starts with the terms $x^2$ and $8x$
is $x^2+8x+16$

Re-write the given equation with the square quadratic at the beginning
$x^2+8x+16-25 = 0$

$(x+4)^2 = 25$

$x+4 = +-sqrt(25)$

$x=-4+-5$

$x=-9$ or $x=1$

How do you solve by completing the square x^2+8x-9=0x^2+8x-9=0?