Question

Find the product (x${}^2$-3xy+2y${}^2$) (2x-3y) and also find its value when x = 4 and y = -3.

• A. 1080
• B. 1190
• C. 1360
• D. 1372

Answer 1

The correct option is B

1190

The given expression is (x${}^2$-3xy+2y${}^2$) (2x-3y)

$\Rightarrow$ x${}^2$(2x-3y)-3xy(2x-3y)+2y${}^2$(2x-3y)

$\Rightarrow$ 2x${}^3$-3x${}^2$y-6x${}^2$y+9xy${}^2$+4xy${}^2$-6y${}^3$

$\Rightarrow$ 2x${}^3$-9x${}^2$y+13xy${}^2$-6y${}^3$

Now, on putting the value x = 4 and y = -3

$\Rightarrow$ 2$\times$(4)${}^3$-9$\times$(4)${}^2$$\times$(-3)+13$\times$4$\times$(-3)${}^2$-6$\times$(-3)${}^3$

$\Rightarrow$ 128+432+468+162 = 1190