What is the derivative of y=cos(^7)base x

The derivative of y=cos(^7)base x is

Dydx = (cos(7x))x⋅(ln(cos(7x))−7x(tan(7x)))

Step-by-step explanation:

step 1 :

y= (cos(7x))x

Take the natural logarithm of either side, bringing the t x down to be the coefficient of the right hand side we get the

step 2 :

⇒ln y = xln (cos (7x))

Differentiate each side with respect to x. The rule of implicit differentiation: ddx (f(y)) = f'(y) ⋅ dydx

step 3 :

∴1y ⋅ dydx  = ddx (x) ⋅ln (cos(7x)) + ddx (ln (cos(7x)))⋅x

Use the chain rule for natural logarithm functions – ddx ( ln (f(x)) )= f'(x)f(x) - we can differentiate the ln (cos (7x))

step 4 :

Ddx (ln (cos(7x))) = −7xsin (7x) cos( 7x 7tan (7x)

Returning to the original equation:

1y ⋅dydx = ln (cos(7x))−7xtan(7x)

Substitute the original y as a function of x value from the start back in.

Dydx = (cos(7x))x⋅(ln(cos(7x))−7x(tan(7x)))