Houghton Mifflin Harcourt Algebra 1, 2015
HM
Houghton Mifflin Harcourt Algebra 1, 2015 View details
1. Understanding Linear Functions
Continue to next subchapter

Exercise 1 Page 170

Can you write the equation in standard form?

Linear? Yes
Graph:

Practice makes perfect
To determine if the given equation is a linear equation, let's first see if we can rewrite it in standard form. Ax+ By= C In this form, A, B, and C are constants and either A or B must be nonzero. We can see that our equation is already in the standard form. Below we have highlighted how it corresponds to the general standard form. 2x+y=4 ⇔ 2x+ 1y= 4

When written this way, we can see that A= 2, B= 1, and C= 4. Since this equation can be written in standard form, it is linear. We will graph this equation by finding and plotting its intercepts, then connecting them with a line. To find the x- and y-intercepts, we will need to substitute 0 for one variable, solve, then repeat for the other variable.

Finding the x-intercept

Think of the point where the graph of an equation crosses the x-axis. The y-value of that ( x, y) coordinate pair is equal to 0, and the x-value is the x-intercept. To find the x-intercept of the given equation, we should substitute 0 for y and solve for x.
2x+y=4
2x+( 0)=4
2x=4
x=2
An x-intercept of 2 means that the graph passes through the x-axis at the point ( 2,0).

Finding the y-intercept

Let's use the same method to find the y-intercept. Consider the point where the graph of the equation crosses the y-axis. The x-value of the ( x, y) coordinate pair at the y-intercept is 0. Therefore, substituting 0 for x will give us the y-intercept.
2x+y=4
2( 0)+y=4
0+y=4
y=4
A y-intercept of 4 means that the graph passes through the y-axis at the point (0, 4).

Graphing the equation

We can now graph the equation by plotting the intercepts and connecting them with a line.