Find x^2+y^2 if x+y=7 and xy+10

Question

Pls answer these questions 

Answer 1

find x^2+y^2 if x+y=7 and xy=10 (you had xy+10;was this a typo ??)

x+y=7

square both sides

x^2+2xy+y^2=49

if xy=10 then 2xy=20

substitute

x^2+20+y^2=49

x^2+y^2=49-20

x^2+y^2=29