Michigan State University - Diagnostic Exam

 [next]  [prev]  [bottom]  [up] 

3.11

  •   The sketch below could describe which function?

    PIC

    1. y = ax2 + bx, a < 0 and b > 0
    2. y = ax2 + c, a < 0 and c < 0
    3. y = ax2 + bx + c, a > 0
    4. y = ax2 + c, a < 0 and c > 0
    5. y = ax2 + bx, a < 0 and b < 0

Solution:
a<0 since the parabola “opens down”. Also, the x-intercepts are c1 < 0 and 0. It follows that

y=a(x- 0)(x - c) = ax2 - ac x ⇒ y = ax2 + bx, a < 0 and b < 0 1 1

Diagnostic:

If you miss this question please review graphs of quadratic functions.

 [next]  [prev]  [top]  [up] 

July 15, 2008