### Home > A2C > Chapter 8 > Lesson 8.2.3 > Problem 8-147

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 2,*” replied Adel, “*so the period must be π*.”

“*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 1 from *x* before multiplying, are parenthesis necessary?

The equation before multiplying by anything.