Question

Expand the following using identies
(5x+y)(5x-4y)

Answer 1

Answer:

By using the identity= (x+a)(x+b)=x²+(a+b)x+ab

Step-by-step explanation:

(5x+y)(5x+(-4y))= 5x²+(y-4y)5x+y×(-4y)

= 25x²-20xy-4y²

Hope you understood!!!

(+)(-)=(-)

(-)(+)=(-)

okk

Answer 2

IT IS OF THE FORM(x+a)(x+b)

THEREFORE,

(5x+y)(5x-4y)

=(5x)^2+(y-4y)5x+[y×(-4y)]

=25x^2+5xy-20xy-4y^2

=25x^2-4y^2-15xy