Question

(x-y)^3+8(x+y)^3 using identity

Answer 1

Answer:

${( x - y)}^{3} = (x - y)({x}^{2} + {y}^{2} - 2xy) \\ = {x}^{3} - {y}^{3} - 3 {x}^{2}y + 3x {y}^{2} \\ { (x + y)}^{3} = {x}^{3} + {y}^{3} + 3 {x}^{2} y + 3 {y}^{2}x \\ {(x - y)}^{3} + 8 {(x + y)}^{3} = \\ {x}^{3} - {y}^{3} - 3 {x}^{2}y + 3x {y}^{2}+8 {x}^{3} + 8 {y}^{3} + 24 {x}^{2} y + 24x {y}^{2} \\ 9 {x}^{3} + 7 {y}^{3} + 21 {x}^{2} y + 27 {y}^{2} x$