# Math

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Find the derivative of f(x)= 2 sqrt x at x=4.

i thought that the derivative would be 2 x^1/2 but I guess this is wrong.

• Math -

dy/dx 2x^(1/2)

2 * 1/2 x^(1/2 - 2/2)
2/2 x^(-1/2) = x^(-1/2) = 1/(sqrt(x))

• Math -

You have two problems here.
1. need D:f(x) = 2sqrtx

2. subsitute x=4 into derivative

D: 2sqrtx :
a) multiply power times coefficient; 1/2 * 2 = 1

b)power - 1 = 1/2 -1 = -1/2

c. f'(x) = x^-1/2 or 1/sqrtx

substitute 4 for x and you should be there

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