Question

(х+y) (3x+y) + (x+3y)(x-y)​

Answer 1

Answer:

(3x²+4xy+y²)+(x²+2yx-3y²)

Step-by-step explanation:

=(х+y) (3x+y) + (x+3y)(x-y)​

=(3x²+xy+3xy+y²)+(x²-yx+3yx-3y²)

=(3x²+4xy+y²)+(x²+2yx-3y²)

Do you need to simplify it further?

Answer 2

$\huge \mathfrak{ \red {answer}}$

$(x + y)(3x + y) + (x + 3y)(x - y) \\ \\ = (3 {x}^{2} + xy + 3xy + {y}^{2} ) + ( {x}^{2} - xy + 3xy - 3 {y}^{2}) \\ \\ = 3 {x}^{2} + xy + 3xy + {y}^{2} + {x}^{2} - xy + 3xy - 3 {y}^{2} \\ \\ = 4 {x}^{2} + 6xy - 2 {y}^{2}$