Question: Find the value of $r$. Answer in simplest fraction form
g(x) = f(rx)
f(x) = -3x + 5
r =
1. **State the problem:** We are given two functions: $$g(x) = f(rx)$$ and $$f(x) = -3x + 5$$. We need to find the value of $$r$$ such that the graph of $$g(x)$$ matches the given description.
2. **Understand the functions:** Since $$g(x) = f(rx)$$, substituting $$f(x)$$ gives:
$$g(x) = -3(rx) + 5 = -3r x + 5$$
3. **Analyze the graphs:** Both lines cross the y-axis at about 5, which matches the constant term 5 in both functions.
4. **Find the x-intercepts:**
- For $$f(x) = -3x + 5$$, set $$f(x) = 0$$:
$$0 = -3x + 5$$
$$3x = 5$$
$$x = \frac{5}{3}$$
- For $$g(x) = -3r x + 5$$, set $$g(x) = 0$$:
$$0 = -3r x + 5$$
$$3r x = 5$$
$$x = \frac{5}{3r}$$
5. **Use the graph information:** The red line $$g(x)$$ crosses the x-axis at about 5, so:
$$\frac{5}{3r} = 5$$
6. **Solve for $$r$$:**
$$\frac{5}{3r} = 5$$
Multiply both sides by $$3r$$:
$$5 = 5 \times 3r$$
$$5 = 15r$$
Divide both sides by 15:
$$r = \frac{5}{15}$$
Simplify the fraction:
$$r = \frac{1}{3}$$
**Final answer:**
$$r = \frac{1}{3}$$