### Home > CC3MN > Chapter 5 > Lesson 5.1.2 > Problem5-21

5-21.

Jamila wants to play a game called “Guess My Line.” She gives you the following hint: “Two points on my line are $(1,1)$ and $(2,4)$.”

1. What is the growth rate of her line? A graph of the line may help.

Growth rate: when $x$ grows by $1$, $y$ grows by $3$.

2. What is the $y$-intercept of her line?

The $y$-intercept is where the line crosses the $y$-axis.

One strategy is to use the slope triangle to continue the line and then simply read the $y$-intercept (where the line crosses the $y$-axis) right off the graph.

$y$-intercept $=(0,−2)$.

3. What is the equation of her line?

Use the rate of growth and the $y$-intercept to write an equation for the line.

$y=mx+b$
$m=$ the rate of growth
$b=$ the $y$-coordinate in the $y$-intercept

$y=3x−2$

Use the eTool below to complete the graph and help solve each part.
Click on the link at right for the full eTool version: 5-21 HW eTool