Question
The quadratic function f(x)=ax2+bx+c is known to pass through the points (-1, 6), (7, 6), and (1, - 6). Find the smallest value of the function.
Answer: Option B
:
B
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B
If the points (-1,6), (7,6),and (1,-6) lie oh the graph of y=ax2+bx+c,
Then 6 = a - b + c, 6 = 49a + 7b + c, -6 = a + b + c.
Solving this system, we get a = 1, b = -6, c = -1.
The graph of f(x) = x2−6x−1 is a parabola that opens upward and the vertex is (−b2a,−D4a)=(3,-10).
Option (b).
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