Answer:
f'(3) = -1/5
Explanation:
f(x) = 5x/(2x -1) = 5/2 + (5/2)/(2x -1) . . . . . rewrite to simplify differentiation
f'(x) = -(5/2)(2)/(2x -1)² = -5/(2x -1)² . . . . . using power rule with power = -1
f'(3) = -5/(2·3 -1)² = -5/25 . . . . . . evaluate for x=3
f'(3) = -1/5
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Comment on the attachment
Many graphing calculators can give a numerical result for the derivative.