Question

two adjacent sides of rectangle are 3x*x -5y*y and 7x*x - xy .find its perimeter

Answer 1

$perimeter = 2 \times sum \: \: of \: \: adjacent \: \: sides) \\ 2 \times (3 {x}^{2} - 5 {y}^{2} \: \: + \: \: 7 {x}^{2} - xy) \\ 20 {x}^{2} - 10 {y}^{2} - 2xy$