Gradient Differentiation 600Ddd
1. **Problem (a):** Find the gradient of the curve $y = 3x^4 - 2x^2 + 5x - 2$ at points $(0, -2)$ and $(1, 4)$.
2. **Formula:** The gradient of a curve at any point is given by the derivative $\frac{dy}{dx}$.
3. **Step:** Differentiate $y$ with respect to $x$:
$$\frac{dy}{dx} = \frac{d}{dx}(3x^4) - \frac{d}{dx}(2x^2) + \frac{d}{dx}(5x) - \frac{d}{dx}(2) = 12x^3 - 4x + 5$$
4. **Evaluate gradient at $x=0$:**
$$\frac{dy}{dx}\bigg|_{x=0} = 12(0)^3 - 4(0) + 5 = 5$$
5. **Evaluate gradient at $x=1$:**
$$\frac{dy}{dx}\bigg|_{x=1} = 12(1)^3 - 4(1) + 5 = 12 - 4 + 5 = 13$$
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6. **Problem (b):** Find coordinates on $y = 3x^2 - 7x + 2$ where gradient is $-1$.
7. **Step:** Differentiate $y$:
$$\frac{dy}{dx} = 6x - 7$$
8. **Set gradient equal to $-1$ and solve for $x$:**
$$6x - 7 = -1$$
$$6x = 6$$
$$x = 1$$
9. **Find $y$ at $x=1$:**
$$y = 3(1)^2 - 7(1) + 2 = 3 - 7 + 2 = -2$$
10. **Coordinates:** $(1, -2)$
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11. **Problem (c):** Find differential coefficient of $y = 3x^2 \sin 2x$.
12. **Step:** Use product rule $\frac{d}{dx}(uv) = u'v + uv'$ where $u=3x^2$, $v=\sin 2x$.
13. **Calculate derivatives:**
$$u' = 6x$$
$$v' = 2 \cos 2x$$
14. **Apply product rule:**
$$\frac{dy}{dx} = 6x \sin 2x + 3x^2 (2 \cos 2x) = 6x \sin 2x + 6x^2 \cos 2x$$