How do you solve $-3x^2-12=14x$ by completing the square?

Question

2043 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-06-23T11:04:25

$x~~ -1.13 or x~~ -3.54$

$-3x^2-12=14x or 3x^2+14x+12 =0 or 3(x^2+14/3x)+12$ or

$3(x^2+14/3x +(7/3)^2)-(3*49/9)+12 =0$

$3(x+7/3)^2-49/3+12 =0$ or

$3(x+7/3)^2-13/3 =0 or 3(x+7/3)^2=13/3$ or

$(x+7/3)^2=13/9 or (x+7/3) = +-sqrt(13)/3$ . Either

$x= -7/3+sqrt13/3 or x= -7/3-sqrt13/3$ or

$x= (sqrt13-7)/3 or x= -(sqrt13+7)/3$ or

$x~~ -1.13(2dp) or x~~ -3.54(2dp)$ [Ans]

How do you solve -3x^2-12=14x-3x^2-12=14x by completing the square?