Multiple Choice
1. Problem: Find the value of $m$ if $3-3i = (m-2)i + 3$.
Rewrite the right side: $(m-2)i + 3 = 3 + (m-2)i$.
Equate real parts: $3 = 3$ (true).
Equate imaginary parts: $-3 = m-2$.
Solve for $m$: $m = -3 + 2 = -1$.
2. Problem: Find the product of roots $\alpha \beta$ of $2x^2 - 4x - 8 = 0$.
Using formula for quadratic $ax^2 + bx + c=0$, product of roots is $\frac{c}{a}$.
Here, $a=2$, $c=-8$.
So, $\alpha \beta = \frac{-8}{2} = -4$.
3. Problem: Find $y$ if $\begin{bmatrix}3 & 5 \\ 8 & y+9\end{bmatrix} \begin{bmatrix}1 & 0 \\ 0 & 1\end{bmatrix} = \begin{bmatrix}3 & 5 \\ 8 & -2y\end{bmatrix}$.
Multiplying by identity matrix leaves the first matrix unchanged.
So, $\begin{bmatrix}3 & 5 \\ 8 & y+9\end{bmatrix} = \begin{bmatrix}3 & 5 \\ 8 & -2y\end{bmatrix}$.
Equate bottom right elements: $y + 9 = -2y$.
Solve: $3y = -9 \Rightarrow y = -3$.
4. Problem: Find $f^2(x)$ if $f(x) = \frac{1}{2}x$.
$f^2(x) = f(f(x)) = f\left(\frac{1}{2}x\right) = \frac{1}{2} \times \frac{1}{2}x = \frac{1}{4}x$.
5. Problem: Solve $|x-5| = -3$.
Absolute value cannot be negative.
No solution, so answer is $\phi$ (empty set).
6. Problem: Find discriminant of $x^2 - 3x - 4 = 0$.
Discriminant $D = b^2 - 4ac$ with $a=1$, $b=-3$, $c=-4$.
Calculate: $D = (-3)^2 - 4(1)(-4) = 9 + 16 = 25$.
7. Problem: Find horizontal component of velocity for projectile launched at $30^\circ$ with initial velocity $20$ m/s.
Horizontal component $= 20 \cos 30^\circ = 20 \times \frac{\sqrt{3}}{2} = 10\sqrt{3} \approx 17.3$ m/s.
8. Problem: In triangle ABC, $a=10$, $b=15$, $\alpha=32^\circ$, find $\beta$.
Use Law of Sines: $\frac{a}{\sin \alpha} = \frac{b}{\sin \beta}$.
Calculate $\sin \beta = \frac{b \sin \alpha}{a} = \frac{15 \times \sin 32^\circ}{10} \approx \frac{15 \times 0.5299}{10} = 0.7949$.
Find $\beta = \sin^{-1}(0.7949) \approx 52.6^\circ$.
9. Problem: Which curve is most appropriate for arcs in rainbow effect?
Answer: Circular arc.
10. Problem: Distance between centers of two circles with radii 4 cm and 5 cm touching externally.
Distance $= 4 + 5 = 9$ cm.
11. Problem: Probability of getting two tails when two coins are tossed.
Total outcomes = 4, only one is two tails.
Probability $= \frac{1}{4}$.
12. Problem: Equation of line of best fit.
Answer: $y = mx + c$.
13. Problem: Angle between tangent line and radius at point P on circle.
Answer: $90^\circ$.
14. Problem: Simplify $\left(\frac{2x^2 - 2x}{x+1}\right) \times \left(\frac{2x^2 + 2x}{x-1}\right)$.
Factor numerators: $2x(x-1)$ and $2x(x+1)$.
Expression becomes $\frac{2x(x-1)}{x+1} \times \frac{2x(x+1)}{x-1} = \frac{2x \cancel{(x-1)}}{x+1} \times \frac{2x (x+1)}{\cancel{(x-1)}}$.
Simplify: $2x \times 2x = 4x^2$.
15. Problem: Find y-intercept of $2x + 3y = 2$.
Set $x=0$, then $3y=2$, so $y=\frac{2}{3}$.
Final answers: i) $-1$, ii) $-4$, iii) $-3$, iv) $\frac{1}{4}x$, v) $\phi$, vi) $25$, vii) $17.3$ m/s, viii) $52.6^\circ$, ix) Circular arc, x) $9$ cm, xi) $\frac{1}{4}$, xii) $y=mx+c$, xiii) $90^\circ$, xiv) $4x^2$, xv) $\frac{2}{3}$.