Derivative Product 09224A
1. **State the problem:** Find the derivative of the function
$$f(x) = \frac{4 - 5x}{2x^2 - 4x} \cdot (-x^4 + 3x - 2)(x^5 - 2x^4)$$
2. **Rewrite the function:** Let
$$g(x) = \frac{4 - 5x}{2x^2 - 4x}$$
and
$$h(x) = (-x^4 + 3x - 2)(x^5 - 2x^4)$$
So,
$$f(x) = g(x) \cdot h(x)$$
3. **Use the product rule:**
The derivative of a product is
$$f'(x) = g'(x)h(x) + g(x)h'(x)$$
4. **Find $g'(x)$:**
Use the quotient rule for
$$g(x) = \frac{u}{v} = \frac{4 - 5x}{2x^2 - 4x}$$
where
$$u = 4 - 5x, \quad v = 2x^2 - 4x$$
The quotient rule is
$$g'(x) = \frac{u'v - uv'}{v^2}$$
Calculate derivatives:
$$u' = -5$$
$$v' = 4x - 4$$
So,
$$g'(x) = \frac{(-5)(2x^2 - 4x) - (4 - 5x)(4x - 4)}{(2x^2 - 4x)^2}$$
Simplify numerator:
$$-5(2x^2 - 4x) = -10x^2 + 20x$$
$$(4 - 5x)(4x - 4) = 16x - 16 - 20x^2 + 20x = -20x^2 + 36x - 16$$
So numerator:
$$-10x^2 + 20x - (-20x^2 + 36x - 16) = -10x^2 + 20x + 20x^2 - 36x + 16 = 10x^2 - 16x + 16$$
Therefore,
$$g'(x) = \frac{10x^2 - 16x + 16}{(2x^2 - 4x)^2}$$
5. **Find $h'(x)$:**
First expand $h(x)$:
$$h(x) = (-x^4 + 3x - 2)(x^5 - 2x^4)$$
Multiply:
$$-x^4 \cdot x^5 = -x^9$$
$$-x^4 \cdot (-2x^4) = +2x^8$$
$$3x \cdot x^5 = 3x^6$$
$$3x \cdot (-2x^4) = -6x^5$$
$$-2 \cdot x^5 = -2x^5$$
$$-2 \cdot (-2x^4) = +4x^4$$
So,
$$h(x) = -x^9 + 2x^8 + 3x^6 - 6x^5 - 2x^5 + 4x^4 = -x^9 + 2x^8 + 3x^6 - 8x^5 + 4x^4$$
Now differentiate term by term:
$$h'(x) = -9x^8 + 16x^7 + 18x^5 - 40x^4 + 16x^3$$
6. **Write the final derivative:**
$$f'(x) = g'(x)h(x) + g(x)h'(x) = \frac{10x^2 - 16x + 16}{(2x^2 - 4x)^2} \cdot (-x^9 + 2x^8 + 3x^6 - 8x^5 + 4x^4) + \frac{4 - 5x}{2x^2 - 4x} \cdot (-9x^8 + 16x^7 + 18x^5 - 40x^4 + 16x^3)$$
This is the derivative of the given function.