Q. Find the derivative of the following function.y=7x2−9xAnswer: y′=
Identify Function Components: Identify the function and its components.We have y=7(x2−9x), which is an exponential function with base 7 and an exponent that is a function of x, namely x2−9x.
Apply Chain Rule: Apply the chain rule for differentiation.The chain rule states that the derivative of a composite function is the derivative of the outer function evaluated at the inner function times the derivative of the inner function.Here, the outer function is au where a is a constant and u is a function of x. The derivative of au with respect to u is au⋅ln(a).The inner function is u(x)=x2−9x. The derivative of u with respect to x is a0.
Differentiate Outer Function: Differentiate the outer function with respect to the inner function.Let's denote the outer function as f(u)=7u. Then, f′(u)=7u⋅ln(7).
Differentiate Inner Function: Differentiate the inner function with respect to x. We have u(x)=x2−9x. The derivative u′(x) is found by differentiating each term separately: u′(x)=dxd(x2)−dxd(9x)u′(x)=2x−9
Apply Chain Rule for Derivative: Apply the chain rule to find the derivative of y with respect to x. Using the chain rule, we get: y′(x)=f′(u(x))⋅u′(x)y′(x)=(7x2−9x⋅ln(7))⋅(2x−9)
Simplify Derivative: Simplify the expression for the derivative.y′(x)=7(x2−9x)⋅ln(7)⋅(2x−9)This is the final form of the derivative.
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