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

1 Answer
Aug 10, 2018

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

Explanation:

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).