Q. Given the function f(x)=−x3+2x3, find f′(3). Express your answer as a single fraction in simplest radical form.Answer: f′(3)=
Find Derivative of f(x): First, we need to find the derivative of the function f(x)=−x3+2x3. To do this, we will use the power rule and the chain rule for derivatives.f(x)=−x3/2+2x1/23Let's differentiate each term separately.
Apply Power Rule: For the first term −x23, we apply the power rule which states that the derivative of xn is n⋅xn−1. The derivative of −x23 is −(23⋅x23−1)=−(23⋅x21).
Combine Derivatives: For the second term (3)/(2x1/2), we also apply the power rule. The derivative of x−1/2 is (−1/2)⋅x−1/2−1=(−1/2)⋅x−3/2.The derivative of (3)/(2x1/2) is (3/2)⋅(−1/2)⋅x−3/2=−(3/4)⋅x−3/2.
Evaluate at x=3: Now, we combine the derivatives of both terms to get the derivative of the entire function f(x).f′(x)=−(23⋅x21)−(43⋅x−23)
Simplify Powers of 3: Next, we need to evaluate the derivative at x=3.f′(3)=−((23)321)−(43)3−23
Substitute Values: We simplify the expression by calculating the powers of 3. 31/2 is the square root of 3, which we can write as 3. 3−3/2 is 1 over the square root of 3 cubed, which simplifies to 1/(33).
Perform Multiplication and Division: Now we substitute these values into the derivative. f′(3)=−(23⋅3)−(43⋅331)
Find Common Denominator: We simplify the expression by performing the multiplication and division.f′(3)=−(233)−(431)
Combine Numerators: To combine these terms into a single fraction, we need a common denominator. The common denominator will be 43. f′(3)=−4363−431
Simplify Numerator: Now we can combine the numerators over the common denominator. f′(3)=43−(63)−1
Simplify Numerator: Now we can combine the numerators over the common denominator.f′(3)=43−(63)−1Finally, we simplify the numerator.f′(3)=43−63−1This is the derivative of the function f(x) at x=3 in simplest radical form.
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