Question

If x + y + z = 12 and x²+ y² + z² = 100, find xy + yz + xz​

Answer 1

Step-by-step explanation:

x+y+z=12

square both the sides

(x+y+z)²=(12)²

x²+y²+z²+2xy+2yz+2xz=144

a/q

x²+y²+z²=100

then

100+2xy+2yz+2xz=144

2(xy+yz+xz)=144-100

xy+yz+xz=44/2

xy+yz+xz=22