Linear Functions 168Ae8
1. **Problem Statement:**
We are given four linear functions defined on the domain $-4 \leq x \leq 6$:
(a) $f(x) = 5x - 2$
(b) $f(x) = 5x + 2$
(c) $f(x) = -5x - 2$
(d) $f(x) = -5x + 2$
2. **Formula and Rules:**
A linear function has the form $f(x) = mx + b$ where $m$ is the slope and $b$ is the y-intercept.
- The slope $m$ tells us how steep the line is and the direction it goes (positive slope means rising, negative means falling).
- The y-intercept $b$ is the point where the line crosses the y-axis (when $x=0$).
- The domain restriction $-4 \leq x \leq 6$ means we only plot points for $x$ values in this range.
3. **Intermediate Work and Explanation:**
- For (a) $f(x) = 5x - 2$:
- Slope $m=5$ (line rises steeply)
- Y-intercept $b=-2$
- Calculate endpoints:
- At $x=-4$, $f(-4) = 5(-4) - 2 = -20 - 2 = -22$
- At $x=6$, $f(6) = 5(6) - 2 = 30 - 2 = 28$
- For (b) $f(x) = 5x + 2$:
- Slope $m=5$
- Y-intercept $b=2$
- Endpoints:
- At $x=-4$, $f(-4) = 5(-4) + 2 = -20 + 2 = -18$
- At $x=6$, $f(6) = 5(6) + 2 = 30 + 2 = 32$
- For (c) $f(x) = -5x - 2$:
- Slope $m=-5$ (line falls steeply)
- Y-intercept $b=-2$
- Endpoints:
- At $x=-4$, $f(-4) = -5(-4) - 2 = 20 - 2 = 18$
- At $x=6$, $f(6) = -5(6) - 2 = -30 - 2 = -32$
- For (d) $f(x) = -5x + 2$:
- Slope $m=-5$
- Y-intercept $b=2$
- Endpoints:
- At $x=-4$, $f(-4) = -5(-4) + 2 = 20 + 2 = 22$
- At $x=6$, $f(6) = -5(6) + 2 = -30 + 2 = -28$
4. **Summary:**
Each function is a straight line with slope and intercept as given. The domain limits the graph to $x$ values between $-4$ and $6$. Plotting the endpoints and connecting them with a straight line will give the graph of each function.
**Final answers:**
- (a) Line from $(-4, -22)$ to $(6, 28)$
- (b) Line from $(-4, -18)$ to $(6, 32)$
- (c) Line from $(-4, 18)$ to $(6, -32)$
- (d) Line from $(-4, 22)$ to $(6, -28)$