展開(いろいろな計算1) 2解説

2. 次の式を展開しなさい。
(4x²-8xy)÷4x+3x+y 5a+b+(8a²-4ab)÷4a (8x²y+4xy²)÷2xy-(5y-2x) x²+4x-(6x²y+12xy-9y)÷3y

①(4x²-8xy)÷4x+3x+y
=4x²4x-8xy4x+3x+y
=x-2y+3x+y
=4x-y

②
5a+b+(8a²-4ab)÷4a
=5a+b+8a²4a-4ab4a
=5a+b+2a-b
=7a

③(8x²y+4xy²)÷2xy-(5y-2x)
=8x²y2xy+4xy²2xy-5y+2x
=4x+2y-5y+2x
=6x-3y

④x²+4x-(6x²y+12xy-9y)÷3y
=x²+4x-6x²y3y-12xy3y+9y3y
=x²+4x-2x²-4x+3
=-x²+3