初二数学整式的乘除与因式分解

问题描述:

初二数学整式的乘除与因式分解
计算
1.(-3x)²-2(2x-5)(x-2)
2.(2x+y-3)(2x-y+3)
2.因式分解
1.m-m³
2.(a-2b)²-2(a+2b)+1
( )×(2a)²=12a四次方-16a³+4a²
..

1.(-3x)²-2(2x-5)(x-2)
=9x²-2(2x²-9x+10)
=9x²-4x²+18x-20
=5x²+18x-20
2.(2x+y-3)(2x-y+3)
=(2x)²-(y-3)²
=4x²-y²+6y-9
m-m³
=m(1-m²)
=m(1-m)(1+m)
(a-2b)²-2(a+2b)+1
=(a-2b)²-2(a-2b)+1-8b
=(a-2b-1)²-8b
()×(2a)²=12a^4-16a³+4a²
(2a)²=4a²
原式=3a²-4a+1=(3a-1)(a-1)