Question

plzzzzz solve the question no 2 and 3 .​

Answer 1

$(3). {(a + b + c)}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2(ab + bc + +ca ) \\ a = x \\ b = y \\ c = - z \\ {x}^{2} + {y}^{2} + { - z}^{2} + 2(xy -yz - zx) \\ {x}^{2} + {y}^{2} - {z}^{2} + 2( xy -yz -zx )$