Which expression makes the equation true? 1.) y^20 = ( )^2 a.) y^4 b.) y^5 c.) y^10 d.) y^12 2.) 100m^20 = ( )^2 a.) 10m^20 b.) 10m^10 c.) 50m^10 d.) 50m^20

1. C. 

The rule of powers is that when a parenthesis is raised to a power, you multiply the two numbers. Since it is being raised to the second power, it needs to have a 10 in the parenthesis. That would make 20. 

2. B

Firstly 10^2 = 100, so we know that the number must be 10. That leaves us with just A and B. Then we know the same thing from the previous equation, that they need to be multiplied together. 

Horizontal change or the change of x