If the points (1, y1) and (-1, y2) lie on the graph of
y = ax2 + bx + c, and the two points are such that y1 – y2 = -6, then b equals:
- -3
- 0
- 3
- ac
- a + c/2
y = ax2 + bx + c
(1, y1): | a + b + c | = | y1 |
(-1, y2): | a – b + c | = | y2 |
0 + 2b + 0 | = | y1 – y2 = -6 | |
2b | = | -6 | |
b | = | -3. |
The answer is (a).