Question

The axis of symmetry for the graph of the function f(x) =

-x2 + bx + 10 is x=6. What is the value of b?
--3
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Answer 1

12

Explanation:

`y = - x {}^(2) + bx + 10 \\ y = - (x {}^(2) - bx - 10) \\ y = -( (x - (b)/(2) ) {}^(2) - \frac{b {}^(2) }{4} - 10) \\ y = - (x - (b)/(2) ) {}^(2) + 10 + \frac{b {}^(2) }{4} \\ \\ therefore \: (b)/(2) = 6 \\ b = 12`