1. **Solve the system of equations using the graphical method:**
Given:
$$\begin{cases} 3x - y = 7 \\ 2x + 3y = 1 \end{cases}$$
Step 1: Express each equation in slope-intercept form $y = mx + b$.
For the first equation:
$$3x - y = 7 \implies -y = 7 - 3x \implies y = 3x - 7$$
For the second equation:
$$2x + 3y = 1 \implies 3y = 1 - 2x \implies y = \frac{1 - 2x}{3} = -\frac{2}{3}x + \frac{1}{3}$$
Step 2: Plot both lines on the coordinate plane.
Step 3: Find the intersection point of the two lines by solving the system algebraically.
Set the right sides equal:
$$3x - 7 = -\frac{2}{3}x + \frac{1}{3}$$
Multiply both sides by 3 to clear denominators:
$$3(3x - 7) = 3\left(-\frac{2}{3}x + \frac{1}{3}\right) \implies 9x - 21 = -2x + 1$$
Add $2x$ to both sides:
$$9x + 2x - 21 = 1 \implies 11x - 21 = 1$$
Add 21 to both sides:
$$11x = 22$$
Divide both sides by 11:
$$x = \cancel{\frac{11x}{11}} = \cancel{\frac{22}{11}} = 2$$
Step 4: Substitute $x=2$ into one of the original equations to find $y$.
Using $y = 3x - 7$:
$$y = 3(2) - 7 = 6 - 7 = -1$$
**Solution:**
$$(x, y) = (2, -1)$$
2. **Graph the inequality $2x + 3y \leq 1$ to find the solution set:**
Step 1: Rewrite the inequality in slope-intercept form:
$$2x + 3y \leq 1 \implies 3y \leq 1 - 2x \implies y \leq \frac{1 - 2x}{3} = -\frac{2}{3}x + \frac{1}{3}$$
Step 2: Graph the boundary line $y = -\frac{2}{3}x + \frac{1}{3}$ (solid line because of \(\leq\)).
Step 3: Shade the region below the line because $y$ is less than or equal to the expression.
3. **Graph the system of inequalities:**
$$\begin{cases} y \leq 2x - 3 \\ y \geq -3 \\ y \leq -1.25x + 2.5 \end{cases}$$
Step 1: Graph each boundary line:
- $y = 2x - 3$ (solid line, shade below)
- $y = -3$ (horizontal line, shade above)
- $y = -1.25x + 2.5$ (solid line, shade below)
Step 2: The solution set is the intersection of all shaded regions.
4. **Solve the system using the elimination method:**
$$\begin{cases} \frac{3}{2}x + \frac{1}{2}y = -3 \\ \frac{1}{2}y = x + 2 \end{cases}$$
Step 1: Rewrite the second equation:
$$\frac{1}{2}y = x + 2 \implies y = 2x + 4$$
Step 2: Substitute $y = 2x + 4$ into the first equation:
$$\frac{3}{2}x + \frac{1}{2}(2x + 4) = -3$$
Simplify:
$$\frac{3}{2}x + x + 2 = -3$$
Combine like terms:
$$\frac{3}{2}x + x = \frac{3}{2}x + \frac{2}{2}x = \frac{5}{2}x$$
So:
$$\frac{5}{2}x + 2 = -3$$
Subtract 2 from both sides:
$$\frac{5}{2}x = -5$$
Multiply both sides by $\frac{2}{5}$:
$$x = -5 \times \frac{2}{5} = -2$$
Step 3: Substitute $x = -2$ into $y = 2x + 4$:
$$y = 2(-2) + 4 = -4 + 4 = 0$$
**Solution:**
$$(x, y) = (-2, 0)$$
Linear Systems 6A6F53
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