Inequality System
1. Stating the problem: Solve the system of inequalities
(a) $3x + 2x(x - 3) \leq 2(5 + x^2)$
(b) $6 - 2 + 3x + 4x \leq 9$
2. Solve inequality (a):
Start by expanding and simplifying both sides.
Left side: $3x + 2x(x - 3) = 3x + 2x^2 - 6x = 2x^2 - 3x$
Right side: $2(5 + x^2) = 10 + 2x^2$
Rewrite inequality:
$$2x^2 - 3x \leq 10 + 2x^2$$
Subtract $2x^2$ from both sides:
$$2x^2 - 3x - 2x^2 \leq 10 + 2x^2 - 2x^2 \Rightarrow -3x \leq 10$$
Divide both sides by $-3$ and reverse inequality sign (dividing by negative):
$$x \geq -\frac{10}{3}$$
3. Solve inequality (b):
Simplify left side:
$$6 - 2 + 3x + 4x = 4 + 7x$$
Inequality becomes:
$$4 + 7x \leq 9$$
Subtract 4 from both sides:
$$7x \leq 5$$
Divide both sides by 7:
$$x \leq \frac{5}{7}$$
4. Combine solutions for the system:
$$x \geq -\frac{10}{3} \quad \text{and} \quad x \leq \frac{5}{7}$$
Therefore, the solution set is:
$$\boxed{-\frac{10}{3} \leq x \leq \frac{5}{7}}$$