Combining squares

Question

The combined area of two squares is 45 square centimeters. Each square is twice as long as a side of the other square. What is the length of each side of the larger square? 

Answer 1

n and 2n are the sides

n^2+(2n)^2=45

n^2+4n^2=45

5n^2=45

n^2=9

n=3 cm

2n=6 cm (answer)