Question

how do you solve this? please explain

Answer 1

Quick steps to solve this.

1. Lets square both. (X +Y)*2 = 7*7 
2. Then, X*2 + 2XY + Y*2 = 49
3. Since XY is given to 4, X*2 + 8 + Y*2 = 49
4. Move 8
5. X*2 + Y*2 = 49 - 8
6. X*2 + Y*2 = 41

The answer is "41"  Boom!