How do you use the product rule to find the derivative of y=(1/x^2-3/x^4)*(x+5x^3)y=(1x23x4)(x+5x3) ?

1 Answer

The Answer is

y'=(1/x^2-3/x^4)*(1+15x^2)+(-2/x^3+12/x^5)(x+5x^3)

Solution :
Suppose we have y=f(x)*g(x)
Then, using Product Rule, y'=f(x)*g'(x)+f'(x)*g(x)

In simple language, keep first term as it is and differentiate the second term, then differentiate the first term and keep the second term as it is or vice-versa.

So, here if we consider,

f(x)=(1/x^2-3/x^4)
g(x)=(x+5x^3)

Then,

f'(x)=(-2/x^3+12/x^5)
g'(x)=(1+15x^2)

Hence, using the product rule,

y'=(1/x^2-3/x^4)(1+15x^2)+(-2/x^3+12/x^5)(x+5x^3)

In case , if we have more than two function, let see

y=u(x)*v(x)*w(x)

then,

y'=u'(x)*v(x)*w(x)+u(x)*v'(x)*w(x)+u(x)*v(x)*w'(x)

i.e. differentiate one function at a time and keep the remaining two as it is or consider them as constant and similarly follow for the remaining two.