Question

Solve -3x^2+3-x=90=0 using quadratic formula

Answer 1

@Kainui

Answer 2

here are the choices:

Answer 3

Since 30 is not an odd number, its fine to use the completing the square method, but i dont really like it

Answer 4

\[x1,2 = \frac{ -30\pm \sqrt{30^2-4\times(-3)\times(-90)} }{ 2\times(-3) }\]

Answer 5

i got it, but im stuck on the last step

Answer 6

\[x1,2 = 5 \pm \frac{ \sqrt{-180} }{ -6 } \]

Answer 7

wait why the 5?

Answer 8

its supposed to be a 30

Answer 9

oh i get it

Answer 10

now we can insert the -6 into the square root - it becomes 36:
\[x1,2 = 5 \pm \sqrt{\frac{ -180}{ 36 }}\]

Answer 11

now -180/36 = -5
so square root of -5 is
i times square root of 5

Answer 12

ok?

Answer 13

ok its B thanks