Q. 3. (6 pts) Use logarithmic differentiation to find the derivative ofy=(10x2+1)cosx
Apply Logarithmic Differentiation: First, we need to apply logarithmic differentiation. To do this, we take the natural logarithm of both sides of the equation y=(10x2+1)cosx.We get ln(y)=ln((10x2+1)cosx).Using the property of logarithms that allows us to bring the exponent in front, we get ln(y)=cos(x)⋅ln(10x2+1).
Differentiate with Respect to x: Next, we differentiate both sides of the equation with respect to x. The left side becomes the derivative of ln(y) with respect to y, multiplied by the derivative of y with respect to x (by the chain rule), which is (1/y)⋅dxdy. The right side will require the product rule since it is the product of two functions of x, cos(x) and ln(10x2+1). So, we have x0.
Solve for dy/dx: Now we need to solve for dxdy. We multiply both sides of the equation by y to isolate dxdy on one side.dxdy=y⋅(−sin(x)⋅ln(10x2+1)+cos(x)⋅(10x2+11)⋅(20x)).
Substitute Original y: We substitute back the original y from y=(10x2+1)cosx into the equation.dxdy=(10x2+1)cosx∗(−sin(x)∗ln(10x2+1)+cos(x)∗(10x2+11)∗(20x)).
Simplify the Expression: Finally, we simplify the expression to get the final answer. dxdy=(10x2+1)cosx∗(−sin(x)∗ln(10x2+1)+10x2+120x∗cos(x)).
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