Question

What are the solutions of 3x2 + 15 = -6x?

-1 ± i

-1 ± 2i

-2 ± i

-2 ± 2i

Answer 1

@student_basil?

Answer 2

@amistre64?

Answer 3

\[ x= -1\pm 2 i

\]

Answer 4

\[
3 x^2+15=-6 x \\
3 x^2 + 6 x +15=0\\

b^2-4 a c=36 -180= - 1 44\\
\sqrt{b^2-4 a c}= 12 i\\
x=\frac{-6\pm 12i}{6}= -1\pm 2i
\]