Solve 3x2 = −12x − 15.

x = −4 ± 2i
x = −4 ± i
x = −2 ± 2i
x = −2 ± i

ANSWER



EXPLANATION

We use the method of completing the squares.

The equation is


We rewrite the above equation to obtain;



We divide through by 3 to obtain;



We add half the coefficient of


to both sides of the equation to get,



The right hand side is now a perfect square.



We now take square root of both sides to get;



We add -2 to both sides,



We simplify to obtain,