How Solve it? Differentiate this function, thank you!

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1 Answer
Mar 15, 2017

(df)/(dx)=20x(4x^2-7x-8)(6x^2-7x-4)dfdx=20x(4x27x8)(6x27x4)

Explanation:

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(4x27x8)2

= 5x^2(4x^2-7x-8)(4x^2-7x-8)5x2(4x27x8)(4x27x8)

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(4x27x8)(4x27x8)+(8x7)×5x2(4x27x8)+(8x7)×5x2(4x27x8)

= 10x(4x^2-7x-8)^2+2xx5x^2(8x-7)(4x^2-7x-8)10x(4x27x8)2+2×5x2(8x7)(4x27x8)

= 10x((4x^2-7x-8)^2+x(8x-7)(4x^2-7x-8))10x((4x27x8)2+x(8x7)(4x27x8))

= 10x(4x^2-7x-8)((4x^2-7x-8)+x(8x-7))10x(4x27x8)((4x27x8)+x(8x7))

= 10x(4x^2-7x-8)(4x^2-7x-8+8x^2-7x)10x(4x27x8)(4x27x8+8x27x)

= 10x(4x^2-7x-8)(12x^2-14x-8)10x(4x27x8)(12x214x8)

= 20x(4x^2-7x-8)(6x^2-7x-4)20x(4x27x8)(6x27x4)