Question

find the product (xy+3)(xy-5) ​

Answer 1

We simply substitute x=4,y=5 in the given product −3y(xy+y 2 ) as follows:

−3y(xy+y 2 )

=−(3×5)((4×5)+5 2 )

=−15(20+25)

=−15×45

=−675

Hence, −3y(xy+y 2)=−675 when x=4,y=5.

Answer 2

$\Huge\sf\red{answer:}$

$\sf{ }$

$\bf{{\underline{To~solve}}:}$

$\sf{~~~~~~ (xy+3)(xy-5)}$

$\bf{Identity:~(x+a)(x+b)=x^{2}+(a+b)x+ab}$

$\sf{:→ (xy)^{2}+[3+(-5)~]xy+[3×(-5)~]}$

$\sf{:→ x^{2}y^{2}+(-2)xy+(-15)}$

$\sf{:→ {\red{\underline{\boxed{\bf x^{2}y^{2}-2xy-15}}}}}$