As we have to find derivative of a product of polynomials, we can use product rule here. It states that if f(x)=g(x)h(x)k(x)f(x)=g(x)h(x)k(x)
then (df)/(dx)=dfdx=
(dg)/(dx)xxh(x)xxk(x)+(dh)/(dx)xxg(x)xxk(x)+(dk)/(dx)xxg(x)xxh(x)dgdx×h(x)×k(x)+dhdx×g(x)×k(x)+dkdx×g(x)×h(x)
Here f(x)=5x^2(4x^2-7x-8)^2f(x)=5x2(4x2−7x−8)2
= 5x^2(4x^2-7x-8)(4x^2-7x-8)5x2(4x2−7x−8)(4x2−7x−8)
Hence (df)/(dx)=dfdx=
5xx2x(4x^2-7x-8)(4x^2-7x-8)+(8x-7)xx5x^2(4x^2-7x-8)+(8x-7)xx5x^2(4x^2-7x-8)5×2x(4x2−7x−8)(4x2−7x−8)+(8x−7)×5x2(4x2−7x−8)+(8x−7)×5x2(4x2−7x−8)
= 10x(4x^2-7x-8)^2+2xx5x^2(8x-7)(4x^2-7x-8)10x(4x2−7x−8)2+2×5x2(8x−7)(4x2−7x−8)
= 10x((4x^2-7x-8)^2+x(8x-7)(4x^2-7x-8))10x((4x2−7x−8)2+x(8x−7)(4x2−7x−8))
= 10x(4x^2-7x-8)((4x^2-7x-8)+x(8x-7))10x(4x2−7x−8)((4x2−7x−8)+x(8x−7))
= 10x(4x^2-7x-8)(4x^2-7x-8+8x^2-7x)10x(4x2−7x−8)(4x2−7x−8+8x2−7x)
= 10x(4x^2-7x-8)(12x^2-14x-8)10x(4x2−7x−8)(12x2−14x−8)
= 20x(4x^2-7x-8)(6x^2-7x-4)20x(4x2−7x−8)(6x2−7x−4)