原意是:3X -6xy+7y +A=
错后是:3X -6xy+7y -A=6X +5XY+8y 先求A
A=3X -6xy+7y - (6X +5XY+8y )[被减数-差=减数A]
=3X -6xy+7y -6X -5XY-8y [合并同类项]
=-3X -11xy -y
正确答案:3X -6xy+7y +(-3X -11xy -y )
=3X -6xy+7y -3X -11xy -y
=-17 xy+6 y
原意是:3X -6xy+7y +A=
错后是:3X -6xy+7y -A=6X +5XY+8y 先求A
A=3X -6xy+7y - (6X +5XY+8y )[被减数-差=减数A]
=3X -6xy+7y -6X -5XY-8y [合并同类项]
=-3X -11xy -y
正确答案:3X -6xy+7y +(-3X -11xy -y )
=3X -6xy+7y -3X -11xy -y
=-17 xy+6 y