Question

Can someone explain to me how y=-3x^2 + 5x by completing the square turn to: -3[(x-5/6)^2 - 25/36] and then -3[(x-5/6)^2-25/12] Thank you!

Answer 1

\[y = -3x ^{2} + 5x\]
\[= -3[(x-5/6)^{2} - 25/36]\]
= \[-3[(x-5/6)^{2} - 25/12]\]

Answer 2

where did you get 1/2 x 5?

Answer 3

So you add 25/4 inside the parentheses to complete the square but since there is a -3 outside the parentheses, you are effectively subtracting 75/4 so you must add that back to keep from changing the problem.

Answer 4

ohhh, I basically just multiply -25/36 from -3 to get -25/12?

Answer 5

Yes