5130489
Solve \(1.5x - 3 = 1.5\) in two ways.
a) Interpret the equation as finding the point on \(f(x) = 1.5x - 3\) whose y-coordinate is \(1.5\). Use the slope and y-intercept to identify the x-coordinate.
b) Solve the equation algebraically using equivalent transformations. Compare the results.
Hints
- Where does the graph of \(f\) cross the y-axis?
- How can the slope help you locate the output \(1.5\) from the y-intercept?
- Which operation undoes subtracting \(3\)?
Solution
1. The function \(f(x) = 1.5x - 3\) has y-intercept \(-3\) and slope \(1.5 = \frac{3}{2}\). From \((0, -3)\), moving \(3\) units right changes \(y\) by \(1.5 \cdot 3 = 4.5\), reaching the point \((3, 1.5)\). Thus, \(x = 3\).
2. Algebraically, add \(3\) to both sides: \(1.5x = 4.5\).
3. Divide by \(1.5\): \(x = 3\). The algebraic solution agrees with the slope-and-intercept reasoning.
Answer
\(x = 3\)
