Post

Created by @nathanedwards
 at November 1st 2023, 4:29:24 pm.

Question:

Find the derivative of the function:

f(x)=3x25x+24x3+2x1f(x) = \frac{3x^2 - 5x + 2}{4x^3 + 2x - 1}

Answer:

To find the derivative of the given function, we will use the quotient rule. The quotient rule states that for two functions u(x)u(x) and v(x)v(x),

(u(x)v(x))=u(x)v(x)u(x)v(x)(v(x))2\left(\frac{u(x)}{v(x)}\right)' = \frac{u'(x)v(x) - u(x)v'(x)}{(v(x))^2}

Let's first find the derivatives of the numerator and denominator separately.

Numerator (u(x)u(x)): Using the power rule and the sum/difference rule, we have:

u(x)=3x25x+2u(x) = 3x^2 - 5x + 2
u(x)=ddx(3x2)ddx(5x)+ddx(2)u'(x) = \frac{d}{dx}(3x^2) - \frac{d}{dx}(5x) + \frac{d}{dx}(2)
u(x)=6x5u'(x) = 6x - 5

Denominator (v(x)v(x)): Using the power rule and the sum/difference rule, we have:

v(x)=4x3+2x1v(x) = 4x^3 + 2x - 1
v(x)=ddx(4x3)+ddx(2x)ddx(1)v'(x) = \frac{d}{dx}(4x^3) + \frac{d}{dx}(2x) - \frac{d}{dx}(1)
v(x)=12x2+2v'(x) = 12x^2 + 2

Using the quotient rule, we can now find the derivative of the function:

f(x)=(u(x)v(x)u(x)v(x))(v(x))2f'(x) = \frac{(u'(x)v(x) - u(x)v'(x))}{(v(x))^2}
f(x)=(6x5)(4x3+2x1)(3x25x+2)(12x2+2)(4x3+2x1)2f'(x) = \frac{(6x - 5)(4x^3 + 2x - 1) - (3x^2 - 5x + 2)(12x^2 + 2)}{(4x^3 + 2x - 1)^2}

Expanding and simplifying the numerator:

f(x)=24x4+12x26x20x310x+536x46x2+60x2+10x24x24(4x3+2x1)2f'(x) = \frac{24x^4 + 12x^2 - 6x - 20x^3 - 10x + 5 - 36x^4 - 6x^2 + 60x^2 + 10x - 24x^2 - 4}{(4x^3 + 2x - 1)^2}
f(x)=12x4+36x3+32x226x+1(4x3+2x1)2f'(x) = \frac{-12x^4 + 36x^3 + 32x^2 - 26x + 1}{(4x^3 + 2x - 1)^2}

Simplifying the expression, we get the final answer:

f(x)=12x4+36x3+32x226x+1(4x3+2x1)2f'(x) = \frac{-12x^4 + 36x^3 + 32x^2 - 26x + 1}{(4x^3 + 2x - 1)^2}

Therefore, the derivative of the given function is 12x4+36x3+32x226x+1(4x3+2x1)2\frac{-12x^4 + 36x^3 + 32x^2 - 26x + 1}{(4x^3 + 2x - 1)^2}.