Question

Solve 5x^2 = -30x - 65.

Answer 1

I think it's x= -3 + 4i but i'm not sure.

Answer 2

well rewrite it and divide every term by 5

\[x^2 + 6x = 13\]

complete the square

\[x^2 + 6x + 9 = 13 + 9\]

which becomes

\[(x + 3)^2 = 22\]

now you can solve for x

Answer 3

I'm not sure what to substitute in for x... @campbell_st

Answer 4

Wait, is it x = -6 + 2i

Answer 5

@campbell_st

Answer 6

How were you taught to solve this type problem?

Answer 7

I wasn't that's the thing.

Answer 8

There are 3 ways
(1) factoring (won't work for this problem)
(2) quadratic formula
(3) complete the square

any sound familiar?

Answer 9

I know factoring..that's it

Answer 10

I would start with
5x^2 = -30x - 65

and put it into standard form. Can you do that ?

Answer 11

ok so if

\[(x + 3)^2 = 22\]

taking the square root of both sides gives

\[x + 3 = \pm \sqrt{22}\]

perhaps this helps... to solve for x

Answer 12

standard form means
ax^2 + bx + c = 0