Q. - Let f be a function such that f(1)=0 and f′(1)=−7.- Let g be the function g(x)=x.Evaluate dxd[g(x)f(x)] at x=1.
Apply Quotient Rule: Apply the quotient rule to find the derivative of g(x)f(x). The quotient rule states that if you have a function h(x)=v(x)u(x), then h′(x)=(v(x))2u′(x)v(x)−u(x)v′(x). Here, u(x)=f(x) and v(x)=g(x)=x.
Differentiate f(x) and g(x): Differentiate f(x) and g(x) with respect to x. We are given that f′(1)=−7, but we do not have a general expression for f′(x). However, we only need its value at x=1. To differentiate g(x)=x, we use the power rule. The derivative of x1/2 is g(x)0. So, g(x)1.
Evaluate Derivatives at x=1: Evaluate the derivatives at x=1. We have f′(1)=−7 and g′(1)=(21)(1)−21=21.
Plug Values into Formula: Plug the values into the quotient rule formula.Using the values from Step 3, we get:h′(1)=(g(1))2f′(1)g(1)−f(1)g′(1).We know that f(1)=0 and g(1)=1=1.So, h′(1)=(1)2(−7×1−0×(21)).
Simplify Expression: Simplify the expression to find the derivative at x=1.h′(1)=($−7 - 0) / 1.\)h′(1)=−7.
More problems from Find derivatives of sine and cosine functions