Question

ifx2+y2+z2 =78 and xy +zy+ zx = 59 then find the value of x+y+z​

Answer 1

Answer:

Squaring both sides

(x+y+z)^2 = x^2+y^2+z^2+2(xy+yz+zx)

we can substitute given values

(x+y+z) ^2=18+(2×9)

(x+y+z)^2=36

(x+y+z)=6