Given that the maximum value of quadratic function F X = kx2 + 2kx + 1 in the interval [- 2,2] is 9, find the value of real number K

Because the maximum value of F (x) = kx2 + 2kx + 1 in the interval [- 2,2] is 9
Axis of symmetry x = - 2K / 2K = - 1
When K0, when x = 2, take the maximum, f (2) = 4K + 4K + 1 = 9, k = 1
So k = 1 or - 8

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