Question

Use the zeros of the following quadratic to find the x-value of the vertex.

y = x^2 + 2x -8
A. 2
B. 1
C. -1
D. -8
PLEASE HELP ASAP

Answer 1

Just use the following formula:

`v= ((-b)/(2a), f( (-b)/(2a)))`

In this problem, b=2 and a=1

Substitute the values into the formula.

v=(-(2)/2(1), f(-(2)/2(1)))
v=(-1,f(-1))
v=(-1,(-1)²+2(-1)-8)
v=(-1,(1-2-8))
v=(-1,-9)

Therefore, the vertex is (-1,-9).

However, you only wanted the x-value which is in fact -1.

Therefore, the correct answer is "C. -1."


To use the zeroes, just solve the quadratic and find the mean of the two zeroes.

So,

`m=(x_(1)+x_(2) )/(2)`.


Hope this helps!