Question

Find the value of (x + y )2 + (x - y ) 2

Answer 1

Answer:

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