Question

Solve 3x^2=-30x+24?
I know that I need to use the quadratic formula, but I am really lost... :/

Answer 1

3x^2=-30x+24

3x^2+30x-24 = 0

3(x^2 + 10x - 8) = 0

x^2 + 10x - 8 = 0/3

x^2 + 10x - 8 = 0



a = 1, b = 10, c = -8



\[\Large x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}\]


\[\Large x = \frac{-(10)\pm\sqrt{(10)^2-4(1)(-8)}}{2(1)}\]


\[\Large x = \frac{-10\pm\sqrt{100-(-32)}}{2}\]


\[\Large x = \frac{-10\pm\sqrt{100+32}}{2}\]


I'll let you finish. Remember to simplify as much as you can.

Answer 2

When dividing, I divide both -10 and the sqrt of 132 by 2, correct?

Answer 3

well you first simplify sqrt(132) to get

sqrt(132)

sqrt(4*33)

sqrt(4)*sqrt(33)

2*sqrt(33)

So sqrt(132) simplifies to 2*sqrt(33)

Answer 4

then you would divide both -10 and 2*sqrt(33) by 2

Answer 5

So your answers are

\[\Large x = -5+\sqrt{33} \ \text{or} \ x = -5-\sqrt{33}\]

which you can write them as

\[\Large x = -5 \pm \sqrt{33}\]

Answer 6

Thanks, I wasn't sure how to write it out. When I did it on my own I think I was missing steps and not completing the whole process :)

Answer 7

you're welcome