Question

which equation represents y= -x^2-10x-20 in vertex form?

Answer 1

r u given some options or u wanna express it?

Answer 2

Vertex equation is h=-b/2a
Where h is (h,k) of vertex and a,b is ax^2+bx+c

Answer 3

y= -)x-5)^2+5, y=-(x+5)^5+5, y=-_x-5)^2+15, y= -(x+50+10

Answer 4

vertex is
\[(-\frac{b}{2a},f(-\frac{b}{2a}))\]

Answer 5

thats not a choice

Answer 6

He wasn't attempting to answer it; he was giving you stuff to help you work up to the answer.

Answer 7

oh so once you know the vertex, you can write it in that form easily without completing the square

Answer 8

ok thank yall

Answer 9

i can show you if you like, because it is easy

Answer 10

yes please

Answer 11

ok

Answer 12

we compute
\[-\frac{b}{2a}\] in this case a = -1, b = -10 and so
\[-\frac{b}{2a}=-5\]

Answer 13

so you know it is going to look like
\[y=-(x-(-5))^2 + number\]
i.e.
\[y=-(x+5)^2 + number\] the reason for the - sign out front is that you started with
\[-x^2\]

Answer 14

finding the number is easy. just replace x in the original expression by -5 and see what you get, since it is the second coordinate of the vertex. in this case you get
\[y=-(-5)^2-10\times -5 -20=-25+50-20=25-20=5\]
all these 5s are just a coincidence.
your answer is therefore
\[y=-(x+5)^2+5\]

Answer 15

okay thank u so much..

Answer 16

again the simple way is compute -b/2a and then plug it in for x. you will write y = (x+b/2a)^2 +whatever you got