Q. Given the function f(x)=x−2x3, find f′(3). Express your answer as a single fraction in simplest radical form.Answer: f′(3)=
Apply Differentiation Rules: To find the derivative of the function f(x)=x−2x3, we need to apply the rules of differentiation to each term separately.The derivative of x with respect to x is (1/2)x(−1/2).The derivative of x3 with respect to x is (3/2)x(3/2−1)=(3/2)x(1/2).Therefore, the derivative of f(x) is f′(x)=(1/2)x(−1/2)−2×(3/2)x(1/2).
Derivative of x: Now we simplify the expression for f′(x).f′(x)=(21)x(−21)−3x(21).
Derivative of x3: Next, we evaluate the derivative at x=3.f′(3)=(21)3−21−3(321).
Simplify f′(x): We calculate the values of 3(−1/2) and 3(1/2).3(−1/2) is the reciprocal of the square root of 3, which is 1/3.3(1/2) is the square root of 3, which is 3.So, f′(3)=(1/2)(1/3)−3(3).
Evaluate at x=3: We simplify the expression by finding a common denominator and combining the terms.f′(3)=(21)(31)−3(3) can be written as 231−63.
Calculate 3(−1/2) and 3(1/2): To rationalize the denominator, we multiply the numerator and the denominator by 3. f′(3)=(231−63)∗(33).
Combine Terms: We perform the multiplication to rationalize the denominator.f′(3)=(3−6×3)/(2×3).
Rationalize Denominator: We simplify the expression further. f′(3)=63−18.
Perform Multiplication: Finally, we check if the expression is in its simplest form. Since there are no common factors to cancel out, the expression (3−18)/6 is in its simplest form.
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