Question

Expansion of (x+3y)(x-y)gives

Answer 1

Answer:

(x+3y)(x-y)

x(x-y) +3y(x-y)

x square - xy + 3xy - 3y square

x square + 2 xy - 3y square

x square + ( 3-1) xy -3y square

x square + 3xy - 1 xy - 3y square

x ( x + 3y ) - y ( x + 3y )

(x- y) ( x+ 3y )

x- y = 0

x=+y

and , x+ 3y = 0

x= - 3y

Answer 2

Answer:

 x²+2xy-3y²

Step-by-step explanation:

(x+3y)(x-y)

• multiply x with the whole term (x-y)

  x (x-y) = x²-xy---------[1]

• now, multiply 3y with the whole term (x-y)

3y (x-y) = 3xy-3y²-------[2]

Now, combine [1] and [2]

x²-xy+3xy-3y²

(x+3y)(x-y) =  x²-xy+3xy-3y²

  (x+3y)(x-y) =  x²+2xy-3y²

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