### Home > CCA2 > Chapter 7 > Lesson 7.2.3 > Problem 7-147

Ceirin’s teacher promised a quiz for the next day, so Ceirin called Adel to review what they had done in class.

*“Suppose I have* ,” said Ceirin,

*“what will its graph look like?”*

*“It will be horizontally compressed by a factor of ,” *replied Adel,

*“so the period must be* .”

*“Okay, now let’s say I want to shift it one unit to the right. Do I just subtract from , like always?”*

*“I think so,” *said Adel, *“but let’s check on the graphing calculator.” *They proceeded to check on their calculators. After a few moments they both spoke at the same time.

*“*Rats,” said Ceirin, *“it isn’t right.”*

*“Cool,”* said Adel,* “it works.”*

When they arrived at school the next morning, they compared the equations they had put in their graphing calculators while they talked on the phone. One had , while the other had

*.*

Which equation was correct? Did they both subtract ? Explain. Describe the rule for shifting a graph one unit to the right in a way that avoids this confusion.

If you want to subtract before multiplying, are parenthesis necessary?

The equation is correct. To shift the graph one unit to the right, subtract

*before multiplying by anything.*