1. **Problem statement:**
Given the function $$f(x) = \frac{x^2 + 12}{x - t}$$ with a vertical asymptote at $$x = 2$$, a non-vertical asymptote $$l$$, and the graph crossing the y-axis at point $$P$$. Points $$Q$$ and $$R$$ are stationary points.
We need to find:
(a) The value of $$t$$.
(b) The equation of the non-vertical asymptote $$l$$.
(c) The coordinates of point $$P$$ where the graph crosses the y-axis.
(d) The coordinates of the stationary points using calculus.
---
2. **(a) Find the value of $$t$$:**
The vertical asymptote occurs where the denominator is zero, so:
$$x - t = 0 \implies x = t$$
Given the vertical asymptote is at $$x = 2$$, therefore:
$$t = 2$$
---
3. **(b) Find the non-vertical asymptote $$l$$:**
For large $$|x|$$, divide numerator by denominator using polynomial division:
Divide $$x^2 + 12$$ by $$x - 2$$:
$$
\begin{aligned}
&x^2 \div x = x \\
&x \times (x - 2) = x^2 - 2x \\
&\text{Subtract: } (x^2 + 12) - (x^2 - 2x) = 2x + 12 \\
&2x \div x = 2 \\
&2 \times (x - 2) = 2x - 4 \\
&\text{Subtract: } (2x + 12) - (2x - 4) = 16
\end{aligned}
$$
So,
$$
\frac{x^2 + 12}{x - 2} = x + 2 + \frac{16}{x - 2}
$$
As $$x \to \pm \infty$$, $$\frac{16}{x - 2} \to 0$$, so the non-vertical asymptote is:
$$
\boxed{y = x + 2}
$$
---
4. **(c) Find coordinates of point $$P$$ where the graph crosses the y-axis:**
At the y-axis, $$x = 0$$, so:
$$
f(0) = \frac{0^2 + 12}{0 - 2} = \frac{12}{-2} = -6
$$
Therefore,
$$
P = (0, -6)
$$
---
5. **(d) Find stationary points $$Q$$ and $$R$$ using calculus:**
Stationary points occur where $$f'(x) = 0$$.
Given:
$$
f(x) = \frac{x^2 + 12}{x - 2}
$$
Use quotient rule:
$$
f'(x) = \frac{(2x)(x - 2) - (x^2 + 12)(1)}{(x - 2)^2}
$$
Simplify numerator:
$$
2x(x - 2) - (x^2 + 12) = 2x^2 - 4x - x^2 - 12 = x^2 - 4x - 12
$$
Set numerator equal to zero for stationary points:
$$
x^2 - 4x - 12 = 0
$$
Solve quadratic:
$$
x = \frac{4 \pm \sqrt{(-4)^2 - 4 \times 1 \times (-12)}}{2} = \frac{4 \pm \sqrt{16 + 48}}{2} = \frac{4 \pm \sqrt{64}}{2} = \frac{4 \pm 8}{2}
$$
So,
$$
x_1 = \frac{4 + 8}{2} = 6, \quad x_2 = \frac{4 - 8}{2} = -2
$$
Find corresponding $$y$$ values:
$$
f(6) = \frac{6^2 + 12}{6 - 2} = \frac{36 + 12}{4} = \frac{48}{4} = 12
$$
$$
f(-2) = \frac{(-2)^2 + 12}{-2 - 2} = \frac{4 + 12}{-4} = \frac{16}{-4} = -4
$$
Therefore, stationary points are:
$$
Q = (6, 12), \quad R = (-2, -4)
$$
Function Asymptotes Stationary
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