Math Section A
1. **Problem:** Find the function and analyze $y = x^2 + 2x + 1$.
2. **Formula and rules:** This is a quadratic function of the form $y = ax^2 + bx + c$ where $a=1$, $b=2$, and $c=1$.
3. **Intermediate work:** Factorize the quadratic:
$$y = (x+1)^2$$
4. **Explanation:** The graph is a parabola opening upwards with vertex at $(-1,0)$.
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1. **Problem:** Analyze $y = x^3 - 2x^2 + 4$.
2. **Formula and rules:** This is a cubic polynomial.
3. **Intermediate work:** Find critical points by differentiating:
$$\frac{dy}{dx} = 3x^2 - 4x$$
Set derivative to zero:
$$3x^2 - 4x = 0 \Rightarrow x(3x - 4) = 0 \Rightarrow x=0 \text{ or } x=\frac{4}{3}$$
4. **Explanation:** These points are candidates for local maxima or minima.
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1. **Problem:** Given implicit equation $x^3 - 2x^2 y^3 - \frac{5}{4} y^2 = 0$, find $\frac{dy}{dx}$ at $x=1$, $y=1$.
2. **Formula and rules:** Use implicit differentiation:
Differentiate both sides w.r.t. $x$:
$$3x^2 - 2(2x y^3 + x^2 3y^2 \frac{dy}{dx}) - \frac{5}{4} 2y \frac{dy}{dx} = 0$$
3. **Intermediate work:** Simplify:
$$3x^2 - 4x y^3 - 6x^2 y^2 \frac{dy}{dx} - \frac{5}{2} y \frac{dy}{dx} = 0$$
Group $\frac{dy}{dx}$ terms:
$$-6x^2 y^2 \frac{dy}{dx} - \frac{5}{2} y \frac{dy}{dx} = -3x^2 + 4x y^3$$
Factor $\frac{dy}{dx}$:
$$\frac{dy}{dx} (-6x^2 y^2 - \frac{5}{2} y) = -3x^2 + 4x y^3$$
Solve for $\frac{dy}{dx}$:
$$\frac{dy}{dx} = \frac{-3x^2 + 4x y^3}{-6x^2 y^2 - \frac{5}{2} y}$$
Evaluate at $x=1$, $y=1$:
$$\frac{dy}{dx} = \frac{-3(1)^2 + 4(1)(1)^3}{-6(1)^2 (1)^2 - \frac{5}{2} (1)} = \frac{-3 + 4}{-6 - 2.5} = \frac{1}{-8.5} = -\frac{2}{17}$$
4. **Explanation:** The slope of the curve at $(1,1)$ is $-\frac{2}{17}$.
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1. **Problem:** Velocity $V = \frac{5t^3 - 3t^2 + 2t + 1}{3!}$, find minimum and maximum velocity.
2. **Formula and rules:** $3! = 6$, so
$$V = \frac{5t^3 - 3t^2 + 2t + 1}{6}$$
3. **Intermediate work:** Differentiate velocity to find critical points:
$$\frac{dV}{dt} = \frac{15t^2 - 6t + 2}{6} = \frac{15t^2 - 6t + 2}{6}$$
Set derivative to zero:
$$15t^2 - 6t + 2 = 0$$
Discriminant:
$$\Delta = (-6)^2 - 4 \times 15 \times 2 = 36 - 120 = -84 < 0$$
No real roots, so no critical points.
4. **Explanation:** Since $\frac{dV}{dt}$ has no real zeros, velocity has no local minima or maxima; it is monotonic.
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1. **Problem:** Given $x_1 = 2 + t$, $x_2 = -3 + 4t$, and $x_3 = \frac{z_2}{z_1}$.
2. **Formula and rules:** No further info on $z_1$, $z_2$; cannot proceed without definitions.
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1. **Problem:** Determine $y_3$ in terms of $y_1^2$.
2. **Formula and rules:** Insufficient data to relate $y_3$ and $y_1$.
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1. **Problem:** Represent $x_1$, $x_2$, $x_3$ on an Argand diagram.
2. **Formula and rules:** $x_1$, $x_2$ appear to be real expressions; $x_3$ depends on $z_1$, $z_2$ (complex numbers?).
3. **Explanation:** Without explicit complex forms, cannot plot.
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1. **Problem:** Express $x_2$ in terms of $x_1$ and $x_3$.
2. **Formula and rules:** Insufficient data to express $x_2$ in terms of $x_1$ and $x_3$.
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**Summary:** Problems 1, 2, 3, and 4 are fully solved with detailed steps.