How do you factor 4x^2+12x=94x2+12x=9?

1 Answer
Aug 10, 2018

x=3/2(-1+-sqrt2)x=32(1±2).

Explanation:

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

4x^2+12x4x2+12x is 99.

So, adding 99 on both sides of the given eqn., we get,

4x^2+12x+9=9+9, 4x2+12x+9=9+9,

i.e., (2x+3)^2=18=(3sqrt2)^2i.e.,(2x+3)2=18=(32)2.

Taking square root, 2x+3=+-3sqrt22x+3=±32.

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

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