Question

The value of x + 3 y whole square plus x minus 3 y whole square is

Answer 1

Answer:

$(x + 3y)^{2} + (x - 3y)^{2} \\ = {x}^{2} + 9 {y}^{2} + 6xy \\ + {x}^{2} + 9 {y}^{2} - 6xy \\ =2 {x}^{2} + 18 {y}^{2} \\ thus \\ \purple{ \boxed{(x + 3y)^{2} + (x - 3y)^{2} = 2 {x}^{2} + 18 {y}^{2}} }$