Question

please help with this answer plz​

Answer 1

Answer:

x+y+z =7

squaring on both sides

(x+y+z)²=(7)²

X²+y²+z²+2xy+2yz+2xz=49[ (using identity (a+b+c)² =a²+b²+c²+2ab+2bc+2ca]

x²+y²+z²+2(xy+yz+zx) =49

x² +y²+z² +2*12=49

x²+y²+z²+24=49

x²+y²+z²=49-24

x²+y²+z²=25 ans