Identify Functions: We are given the function y=x3cos(x). To find the derivative of y with respect to x, we will use the quotient rule, which states that the derivative of a function in the form of g(x)f(x) is (g(x))2f′(x)g(x)−f(x)g′(x).
Find Derivatives: First, identify the functions f(x) and g(x) where f(x)=cos(x) and g(x)=x3. Then find their derivatives f′(x) and g′(x). The derivative of f(x)=cos(x) with respect to x is f′(x)=−sin(x). The derivative of g(x)=x3 with respect to x is g(x)1.
Apply Quotient Rule: Now apply the quotient rule. The derivative of y with respect to x is:dxdy=(g(x))2f′(x)g(x)−f(x)g′(x)Substitute f(x), f′(x), g(x), and g′(x) into the formula:dxdy=(x3)2(−sin(x))(x3)−(cos(x))(3x2)
Simplify Expression: Simplify the expression by distributing and combining like terms: dxdy=x6−x3sin(x)−3x2cos(x)
Factor Out x2: We can further simplify the expression by factoring out an x2 from the numerator: dxdy=x6x2(−xsin(x)−3cos(x))
Cancel Out x2: Now, we can cancel out an x2 from the numerator and denominator, as long as x is not equal to 0 (since we cannot divide by zero):dxdy=x4−xsin(x)−3cos(x)
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