Q. Find the derivative of each function using the limit definition.a. f(x)=x2+3x−5
Write Limit Definition: Write down the limit definition of the derivative.The derivative of a function f(x) at a point x is given by the limit as h approaches 0 of the difference quotient: f′(x)=limh→0hf(x+h)−f(x).
Apply to Function: Apply the limit definition to the function f(x)=x2+3x−5. We need to calculate the limit as h approaches 0 of the expression: (f(x+h)−f(x))/h=((x+h)2+3(x+h)−5−(x2+3x−5))/h.
Expand Numerator: Expand the numerator of the difference quotient.Expand (x+h)2 and 3(x+h) in the numerator to get: (x2+2xh+h2+3x+3h−5−x2−3x+5)/h.
Simplify Numerator: Simplify the numerator by canceling out like terms. The terms x2, 3x, and −5 cancel out with −x2, −3x, and +5, respectively, leaving us with: (2xh+h2+3h)/h.
Factor Out h: Factor out h from the numerator.Factor h from each term in the numerator to get: hh(2x+h+3).
Cancel h: Simplify the difference quotient by canceling h. Cancel h in the numerator and denominator to get: 2x+h+3.
Take Limit: Take the limit as h approaches 0. Now we need to find the limit of 2x+h+3 as h approaches 0, which is simply 2x+3 since the term involving h vanishes.
Write Final Derivative: Write down the final derivative.The derivative of the function f(x)=x2+3x−5 is f′(x)=2x+3.
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