1. **Solve the inequalities:**
a) $8x \leq x^2 + 12$
b) $-x^2 > 8x + 16$
c) $y < -(x+2)(x-4)$
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2. **Check if points $A(3,7)$ and $B(-1,12)$ satisfy $y > 2x^2 - 5x + 4$**
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3. **Find $m$ such that for $(m+1)x^2 - mx + m - 1 = 0$:**
- sum of roots = 4
- product of roots = -5
- no real solution
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4. **Solve systems:**
a) $\begin{cases} y < x + 2 \\ y \geq x^2 - 4 \end{cases}$
b) $\begin{cases} -x^2 + 3x + 10 \geq 0 \\ x^2 - 11x + 28 < 0 \end{cases}$
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5. **Find $m$ so that vertex of $f(x) = mx^2 - 2(m-2)x + m$ lies on the $y$-axis**
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6. **Determine inequalities from the graph description:**
- Parabola opens upward with vertex near $(-1,1)$
- Line passes through origin with positive slope
- Shaded region is to the left of parabola and below the line
- Conditions: $a > 0$, $\Delta < 0$
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### Step 1: Solve $8x \leq x^2 + 12$
Rewrite as:
$$x^2 - 8x + 12 \geq 0$$
Factor:
$$x^2 - 8x + 12 = (x - 6)(x - 2)$$
Inequality:
$$(x - 6)(x - 2) \geq 0$$
This holds when $x \leq 2$ or $x \geq 6$.
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### Step 2: Solve $-x^2 > 8x + 16$
Rewrite:
$$-x^2 - 8x - 16 > 0$$
Multiply both sides by $-1$ (flip inequality):
$$x^2 + 8x + 16 < 0$$
Factor:
$$x^2 + 8x + 16 = (x + 4)^2$$
Since $(x + 4)^2 \geq 0$ always, and equals zero at $x = -4$, the inequality $< 0$ has no solution.
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### Step 3: Solve $y < -(x+2)(x-4)$
Expand:
$$y < -(x^2 - 2x - 8) = -x^2 + 2x + 8$$
This is the region below the parabola $y = -x^2 + 2x + 8$.
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### Step 4: Check points for $y > 2x^2 - 5x + 4$
For $A(3,7)$:
Calculate right side:
$$2(3)^2 - 5(3) + 4 = 18 - 15 + 4 = 7$$
Check $7 > 7$? No, equality only, so $A$ does not satisfy strict inequality.
For $B(-1,12)$:
$$2(-1)^2 - 5(-1) + 4 = 2 + 5 + 4 = 11$$
Check $12 > 11$? Yes, so $B$ satisfies.
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### Step 5: Find $m$ for sum and product of roots
Equation:
$$(m+1)x^2 - mx + m - 1 = 0$$
Sum of roots $S = \frac{m}{m+1}$
Product of roots $P = \frac{m-1}{m+1}$
Set sum = 4:
$$\frac{m}{m+1} = 4$$
Multiply both sides:
$$m = 4(m+1)$$
$$m = 4m + 4$$
$$\cancel{m} - 4m = 4$$
$$\cancel{\cancel{m}} - 4m = 4$$
$$-3m = 4$$
$$m = -\frac{4}{3}$$
Set product = -5:
$$\frac{m-1}{m+1} = -5$$
Multiply both sides:
$$m - 1 = -5(m + 1)$$
$$m - 1 = -5m - 5$$
$$m + 5m = -5 + 1$$
$$6m = -4$$
$$m = -\frac{2}{3}$$
For no real solution, discriminant $\Delta < 0$:
$$\Delta = (-m)^2 - 4(m+1)(m-1) = m^2 - 4(m^2 - 1) = m^2 - 4m^2 + 4 = -3m^2 + 4 < 0$$
Solve:
$$-3m^2 + 4 < 0$$
$$-3m^2 < -4$$
$$\cancel{-3}m^2 > \cancel{\frac{4}{3}}$$ (inequality flips because dividing by negative)
$$m^2 > \frac{4}{3}$$
So:
$$m < -\frac{2}{\sqrt{3}} \quad \text{or} \quad m > \frac{2}{\sqrt{3}}$$
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### Step 6: Solve system $\begin{cases} y < x + 2 \\ y \geq x^2 - 4 \end{cases}$
The solution is the intersection of the region below the line $y = x + 2$ and above the parabola $y = x^2 - 4$.
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### Step 7: Solve system $\begin{cases} -x^2 + 3x + 10 \geq 0 \\ x^2 - 11x + 28 < 0 \end{cases}$
Rewrite first inequality:
$$-x^2 + 3x + 10 \geq 0 \Rightarrow x^2 - 3x - 10 \leq 0$$
Factor:
$$(x - 5)(x + 2) \leq 0$$
Solution:
$$-2 \leq x \leq 5$$
Second inequality:
$$x^2 - 11x + 28 < 0$$
Factor:
$$(x - 4)(x - 7) < 0$$
Solution:
$$4 < x < 7$$
Intersection:
$$4 < x \leq 5$$
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### Step 8: Find $m$ so vertex of $f(x) = mx^2 - 2(m-2)x + m$ lies on $y$-axis
Vertex $x$-coordinate:
$$x_v = -\frac{b}{2a} = -\frac{-2(m-2)}{2m} = \frac{2(m-2)}{2m} = \frac{m-2}{m}$$
For vertex on $y$-axis, $x_v = 0$:
$$\frac{m-2}{m} = 0 \Rightarrow m - 2 = 0 \Rightarrow m = 2$$
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### Step 9: Inequalities from graph description
Parabola: $y = a(x+1)^2 + 1$ with $a > 0$ (opens upward)
Line: $y = kx$ with $k > 0$
Shaded region: left of parabola and below line
Inequalities:
$$y \leq a(x+1)^2 + 1$$
$$y \leq kx$$
Since shaded region is left of parabola, $x \leq$ parabola boundary, so rewrite parabola inequality as:
$$x \leq -1 - \sqrt{\frac{y - 1}{a}}$$
But typically, the region is:
$$y \leq kx$$
$$y \leq a(x+1)^2 + 1$$
with $a > 0$ and discriminant $\Delta < 0$ for the parabola's quadratic form.
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**Final answers:**
1a) $x \leq 2$ or $x \geq 6$
1b) No solution
1c) $y < -x^2 + 2x + 8$
2) $A$ does not satisfy, $B$ satisfies
3) Sum roots = 4: $m = -\frac{4}{3}$
Product roots = -5: $m = -\frac{2}{3}$
No real roots: $m < -\frac{2}{\sqrt{3}}$ or $m > \frac{2}{\sqrt{3}}$
4a) $y < x + 2$ and $y \geq x^2 - 4$
4b) $4 < x \leq 5$
5) $m = 2$
6) $y \leq a(x+1)^2 + 1$, $y \leq kx$, with $a > 0$, $k > 0$, and $\Delta < 0$ for parabola
Inequalities Parameters 713Bb5
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