1. **Problem Statement:** Find the slope, y-intercept, and equation of the line for each graph.
2. **Formula for slope:**
$$m=\frac{y_2-y_1}{x_2-x_1}$$
where $(x_1,y_1)$ and $(x_2,y_2)$ are two points on the line.
3. **Equation of a line:**
$$y=mx+b$$
where $m$ is the slope and $b$ is the y-intercept.
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### a) Line passing through points $(-4,-2)$ and $(8,8)$
4. Calculate slope:
$$m=\frac{8-(-2)}{8-(-4)}=\frac{8+2}{8+4}=\frac{10}{12}$$
5. Simplify slope:
$$m=\frac{\cancel{10}}{\cancel{12}}=\frac{5}{6}$$
6. Find y-intercept $b$ by substituting slope and one point into $y=mx+b$:
Using point $(-4,-2)$:
$$-2=\frac{5}{6}(-4)+b$$
$$-2=-\frac{20}{6}+b$$
$$b=-2+\frac{20}{6}=-2+\frac{10}{3}$$
7. Convert $-2$ to fraction:
$$-2=\frac{-6}{3}$$
8. Add fractions:
$$b=\frac{-6}{3}+\frac{10}{3}=\frac{4}{3}$$
9. Equation of the line:
$$y=\frac{5}{6}x+\frac{4}{3}$$
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### b) Line passing through points $(-4,6)$ and $(8,-2)$
10. Calculate slope:
$$m=\frac{-2-6}{8-(-4)}=\frac{-8}{12}$$
11. Simplify slope:
$$m=\frac{\cancel{-8}}{\cancel{12}}=\frac{-2}{3}$$
12. Find y-intercept $b$ by substituting slope and one point into $y=mx+b$:
Using point $(-4,6)$:
$$6=\left(-\frac{2}{3}\right)(-4)+b$$
$$6=\frac{8}{3}+b$$
$$b=6-\frac{8}{3}$$
13. Convert $6$ to fraction:
$$6=\frac{18}{3}$$
14. Subtract fractions:
$$b=\frac{18}{3}-\frac{8}{3}=\frac{10}{3}$$
15. Equation of the line:
$$y=-\frac{2}{3}x+\frac{10}{3}$$
Linear Relations F5340A
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