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Pearson Algebra 1 Common Core, 2011

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Pearson Algebra 1 Common Core, 2011 View details

5. Standard Form

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Exercise 50 Page 327

Can you enter the equation as it is currently written?

Graphing Calculator:

Sketch:

Practice makes perfect

To graph the equation, we first have to write it in slope-intercept form by solving for y.

4x-6y=9

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Write in slope-intercept form

LHS-4x=RHS-4x

- 6y=- 4x+9

LHS * (- 1)=RHS* (- 1)

6y=4x-9

.LHS /6.=.RHS /6.

y=4x/6-9/6

Write as a decimal

y=4x/6-1.5

a/b=.a /2./.b /2.

y=2x/3-1.5

MovePartNumRight

a* b/c=a/c* b

y=2/3x-1.5

Having rewritten the equation, we can enter it in our calculator by pressing the Y= button and typing the function in one of the rows. When the equation has been entered in the calculator, we can push GRAPH to draw it.

To have a better look we will change the size of the window by pressing WINDOW and changing the settings.

From the slope-intercept form we know that the equation intercepts the y-axis at y=- 1.5. It is not that easy to spot the x-intercept from the equation or by looking at the graph. However, by setting y equal to 0 we can algebraically solve for the x-intercept.

y=2/3x-1.5

y= 0

0=2/3x-1.5

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Solve for x

LHS+1.5=RHS+1.5

1.5=2/3x

LHS * 3=RHS* 3

4.5=2x

.LHS /2.=.RHS /2.

2.25=x

Rearrange equation

x=2.25

Now that we know the x-intercept as well, we have enough points to plot the graph of the equation.

Subchapter links

Lesson Check p.325

Practice and Problem-Solving Exercises p.326-328

Standardized Test Prep p.328

Mixed Review p.328