Question

Can someone please help me find b and c so that the parabola y=-3x^2+bx+c has vertex . (8,4)

Answer 1

Use vertex form and put in the vertex. a = -3

Answer 2

use x = -b/2a

Answer 3

\[y=-3(x-8)^{2}+4\]

Answer 4

Now rearrange the right side.

Answer 5

so do i just solve for y

Answer 6

\[y=-3(x ^{2}-16x+64)+4=-3x ^{2}-48x-188\]

Answer 7

\[y=-3x ^{2}-48x-188\]

Answer 8

OK, yea it worked for c=-188 but i put in b=-48 and it said inccorect, i was doing it the way you suggested but i cant seem to figure out what b is

Answer 9

Oh gee. -3 (-16x)= POSITIVE 48x Sorry.

Answer 10

yea i just got it, thanks so much

Answer 11

yw

Answer 12

theres also another problem, i think you were actually helping me out with it last week just wondering if you had time to help me again with it cant seem to figure it out