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Big Ideas Math Algebra 1, 2015

BI

Big Ideas Math Algebra 1, 2015 View details

5. Solving Equations by Graphing

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Exercise 47 Page 266

Make a table of values to find points from the new graphs.

The graph of g is a reflection in the x-axis of the graph of f.

Practice makes perfect

Let's graph f(x) first, then can graph g(x) on the same coordinate plane to compare.

Graphing f(x)

We can make a table of values to find points of the graph of f(x)=6x.

x	6x	f(x)
- 2	6( - 2)	- 12
0	6( 0)	0
2	6( 2)	12

Let's plot these points and connect them with a straight line to obtain the graph of f(x).

graph of f(x)

Graphing g(x)

Now, let's look at how the function g(x)=- f(x) differs from f(x).

x	f(x)	- f(x)	g(x)
- 2	- 12	- (- 12)	12
0	0	- (0)	0
2	12	- (12)	- 12

We can see that the only thing that has changed is the sign of the y-coordinate.

graph of g(x)

The points are at the same distance from the x-axis. We call this a reflection in the x-axis.

Subchapter links

Communicate Your Answer p.261

Monitoring Progress p.262-264

Exercises p.265-266