Question

If (x+y+z) =7 and x2+y2+z2 =13 find the value of ny +yz + zx

Answer 1

Step-by-step explanation:

(x+y+z)²=x²+y²+z²+2(xy+yz+zx)

(7)²=13+2(xy+yz+zx)

49=15(xy+yz+zx)

49-15=xy+yz+zx

34=xy+yz+zx