Question

Multiply out (x2 + 3xy - y)(3x + y) using polynomial long multiplication.A3x3 + 12x2y + xy2 - 3xy - y2B3x3 + 10x2y + 3xy2 - 3xy + y2C3x3 + 10x2y + 3xy2 - 3xy - y2D3x3 + 8x2y + 3xy2 - 3xy - y2

Answer 1

`C.)3x^3+10x^2y+3xy^2-3xy-y^2`

Step-by-step explanation:

Given the multiplication expression:

`(x^2+3xy-y)\mleft(3x+y\mright)`

On expansion:

`\begin{gathered} =x^2(3x)+x^2y+3xy(3x)+3xy(y)-3xy-y^2 \\ =3x^3+x^2y+9x^2y+3xy^2-3xy-y^2^{} \end{gathered}`

Take the sum

`=3x^3+10x^2y+3xy^2-3xy-y^2`

This gives the required product.