### Home > CC3 > Chapter 1 > Lesson 1.1.3 > Problem1-19

1-19.

Use your graphs from problem 1-17 to answer the questions below. 1-19 HW eTool (Desmos).  Homework Help ✎

1. How can the graph for the rule $y=2x+1$ be used to predict the result for an input ($x$-value) of $7$? How can the graph be used to predict the output ($y$-value) associated with an input of $3\frac{1}{2}$?

Trace up from $x=7$. What is the $y$-value of the point?

Trace up from $x=3.5$.

Trace over to the $y$-axis to find the $y$-value.

Trace over to the $y$-axis to find the $y$-value.

2. If you wanted an output of $7$ for the rule $y=-x+4$, what would you need as an input?

What is the $x$-value when $y=7$?

3. For each of the rules in parts (a) through (e) of problem 1-17, where does the graph cross the $y$-axis? Describe any patterns you notice.

Compare the points where the graphs cross the $y$-axis with their equations.

In the eTool below complete the table for each part to graph each rule.
Click the link at right for the full version of the eTool: CC3 1-19 HW eTool