Question

the vertex of a function y=9-8x-x^2 is (-4,25)?

Answer 1

The vertex can be found by the x co-ordinate being, \[\frac{ -b }{ 2a }\]

than just substitute back to find the y co-ordinate.

Answer 2

watch the sign

Answer 3

remember, a = -1

Answer 4

@some_someone i cant message you unless you fann me :P

Answer 5

hello again

Answer 6

\(y=- (b^{2}-4ac)/4a\)

Answer 7

hi

Answer 8

guys i know you guys are trying to help but like ive never done this so idk what you guys are doing .. :(

Answer 9

you are right

Answer 10

it is in fact \((-4,25)\)

Answer 11

y=9-8x-x^2 first rewrite this as y= ax^2 +bx + c:

y = -x^2 - 8x + 9
now compare to
y= ax^2 +bx + c

Answer 12

So a=-1. b=-8.

Now use -b/(2a) to find the x-coordinate of the vertex.

Answer 13

The equation you have is a quadratic. It is a "bowl." Because of the negative sign in front of the quadratic term, the bowl is "upside down" opening up to the bottom. So there is a peak somewhere above this bowl. This peak occurs at (-4,25). Try any point to the left and right of x=-4 and y will always be smaller. That's how you know you found the peak, or the vertex of this parabola.