Question

find f'(x) for f(x)=(x+1)(x-4)​

Answer 1

Answer:

• let f(x) be y:

• Here, we shall use product rule

${ \boxed{ \bf{ \frac{dy}{dx} = { \huge{v} } \frac{du}{dx} + { \huge{u}} \frac{dv}{dx} }}}$

• v is (x - 4)
• u is (x + 1)
• du/dx is 1
• dv/dx is 1

${ \rm{ \frac{dy}{dx} = (x - 4) + (x + 1)}} \\ \\ { \rm{ \frac{dy}{dx} = 2x - 3}}$