If x2 + y2 + z2 = 13 and xy + yz + zx = 11, then find (x + y + z)2 .

32 70 40 35

35

Formula → (a + b)2 = a2 + b2 + 2ab Here two eq. and three variables are given then put z = 0 x2 + y2 = 13 xy = 11 (x + y)2 = ? (x + y)2 = 13 + 2(11) = 35