**Question:**

If x+y+z = 13 and x^2+ y^2 + z^2 = 69, then The value of xy + z(x+y)...??

Yes...now understood.....thanx divya

squaring both side

x^2+y^2+z^2+2xy+2yz+2xz=169

69+2xy+2yz+2xz=169

2(xy+yz+xz)= 169-69

xy+yz+xz= 50

ni aaya

xy+yz+zx=????

Now open the square formula of (x+y+z)^2......

and put all the known values we will get the __ans__

Yes..u rgt...explain plzzzz

Easy 1

ans__-__50