Chúc bạn hok tốt!!
cho mik xin ctlhn nha
a)
( 2x + 1 )² + 2.( 2x + 1 )
= ( 2x + 1 ) . ( 2x + 1 ) + 2 . ( 2x + 1 )
= ( 2x + 1 ) ( 2x + 3 )
= 4x² + 6x + 2x + 3
= 4x² + 8x + 3
b)
x.(2x + y) + y.(2x + y)
= ( x + y ) ( 2x + y )
= 2x² + xy + 2xy + y²
= 2x² + 3xy + y²
c)
y.(x - y) - x - y
= y(x - y) - x + y - 2y
= y(x - y) - (x - y) - 2y
= ( y - 1 ) (x - y) - 2y
= xy - y² - x + y - 2y
=xy - y² - x - y
d)
2y ( x - y )² + x ( y - x )²
= 2y ( x² -2xy + y² ) + x ( y² - 2xy + x² )
= 2x²y - 4xy² + 2y³ + xy² - 2x²y + x³
= ( 2x²y - 2x²y ) - ( 4xy² - xy² ) + x³ + 2y³
= - 3xy² + x³ + 2y³
