PRACTICE SAMPLE
Example: a derivative in two steps
If f(x) = x² − 4x + 3, what is the derivative of the function at x = 3?
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1
First find the derivative:f′(x) = 2x − 4
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2
Substitute x = 3:f′(3) = 2(3) − 4 = 2
At x = 3, the function's rate of change is 2.