a)
C= ( x² - 2y + xy + 1 ) + ( x² + y - x²y² -1 )
C= x² - 2y + xy + 1 + x² + y - x²y² -1
C= ( x² + x² ) + ( -2y +y ) + xy + ( 1-1) - x²y²
C= 2x² - y + xy - x²y²
b )
C= ( x² + y - x²y² - 1 ) - ( x² - 2y + xy + 1 )
C = x² + y - x²y² - 1 - x² + 2y - xy - 1
C = ( x² - x² ) + ( y + 2y ) - x²y² + ( -1-1 ) - xy
C= 3y - x²y² +2 - xy
Cho mik ctlhn ạ