Question

can any one solve 9 this questions plss.....
With steps

Answer 1

$= {(x + y)}^{2} - {(x - y)}^{2} \\ = ( {x}^{2} + {y}^{2} + 2xy) - ( {x}^{2} + {y}^{2} - 2xy) \\ = {x}^{2} + {y}^{2} + 2xy - {x}^{2} + {y}^{2} - 2xy \\ = {x}^{2} - {x}^{2} + {y}^{2} + {y}^{2} + 2xy - 2xy \\ = 2 {y}^{2}$