Question

A projectile is shot into the air following the path h(x)= 3x^2 -12x + 5. At what time value x will it reach a maximum height ?

A. x=1
B. x= 2
C. x= 4
D. x= 5

And please explain !!

Answer 1

The maximum or minimum occurs when x is at the axis of symmetry

it will be a maximum since h(x) opens upward (a>0)

to find the axis of symmetry

h= -b/2a    (ax^2 +bx+c)    so b=-12  and a=3

h = -(-12)/2(3) = 12/6 = 2

x=2