How do you factor $4x^2+12x=9$ ?

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Answer 1 · 2018-08-10T17:34:29

$x=3/2(-1+-sqrt2)$ .

Observe that, the last term obtained on completing the square of

$4x^2+12x$ is $9$ .

So, adding $9$ on both sides of the given eqn., we get,

$4x^2+12x+9=9+9,$

$i.e., (2x+3)^2=18=(3sqrt2)^2$ .

Taking square root, $2x+3=+-3sqrt2$ .

$:. 2x=-3+-3sqrt2=3(-1+-sqrt2)$ .

$:. x=3/2(-1+-sqrt2)$ .

How do you factor 4x^2+12x=94x^2+12x=9?