Question

Help?

Which of the following equations represents a parabola that opens up and has a vertex with a positive x-value?
A. y=-x^2+8x-15
B. y=2x^2-16x+38
C. y=2x^2+16x+24
D. y=-4x^2-14x-12

Answer 1

I think B is the answer

Answer 2

opens up means in y=ax^2+bx+c form, a is positive
not A or D
vertex witha positive x value

for y=ax^2+bx+c
the x value of the vertex is -b/2a

test b and c
B. 2x^2-16x+38
-b/2a=-(-16)/2=16/2=8, that is positive

C. 2x^2+16x+24
-b/2a=-16/2=-8, negative


B is the answer