If the gradient of the curve y = 2kx2 + x + 1 at x = 1 is 9, find k.
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Correct Answer: Option C
Explanation:
y = 2kx2 + x + 1
Gradient function dy/dx = 4kx + 1
at dy/dx = 9, => 9 = 4kx + 1
=> 8 = 4kx, and k = 8/4x.
At x = 1, k = 8/4 = 2
y = 2kx2 + x + 1
Gradient function dy/dx = 4kx + 1
at dy/dx = 9, => 9 = 4kx + 1
=> 8 = 4kx, and k = 8/4x.
At x = 1, k = 8/4 = 2