计算:1.(-2x-7y)^2 2.(-4x-3y)(4x-3y) 3.(-1/2a+2b)(1/2a-2b) 4.(a/3+3)^2+(a/3-3)^2 5.(-x-y-1)(x-y-1)简便运算1.103×97-104^2 2.2012^2-2013×2011

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/26 21:11:51
计算:1.(-2x-7y)^2 2.(-4x-3y)(4x-3y) 3.(-1/2a+2b)(1/2a-2b) 4.(a/3+3)^2+(a/3-3)^2 5.(-x-y-1)(x-y-1)简便运算1.103×97-104^2 2.2012^2-2013×2011

计算:1.(-2x-7y)^2 2.(-4x-3y)(4x-3y) 3.(-1/2a+2b)(1/2a-2b) 4.(a/3+3)^2+(a/3-3)^2 5.(-x-y-1)(x-y-1)简便运算1.103×97-104^2 2.2012^2-2013×2011
计算:1.(-2x-7y)^2 2.(-4x-3y)(4x-3y) 3.(-1/2a+2b)(1/2a-2b) 4.(a/3+3)^2+(a/3-3)^2 5.(-x-y-1)(x-y-1)
简便运算
1.103×97-104^2
2.2012^2-2013×2011

计算:1.(-2x-7y)^2 2.(-4x-3y)(4x-3y) 3.(-1/2a+2b)(1/2a-2b) 4.(a/3+3)^2+(a/3-3)^2 5.(-x-y-1)(x-y-1)简便运算1.103×97-104^2 2.2012^2-2013×2011
1.(-2x-7y)^2 =4x²+28xy+49y²
2.(-4x-3y)(4x-3y)
=9y²-16x²
3.(-1/2a+2b)(1/2a-2b)
=-(1/2a-2b)²
=-1/4a²+2ab-4b²
4.(a/3+3)^2+(a/3-3)^2
=a²/9+2a+9+a²/9-2a+9
=2a²/9+18
5.(-x-y-1)(x-y-1)
=(y+1+x)(y+1-x)
=(y+1)²-x²
=y²+2y+1-x²
1.103×97-104^2
=(100+3)(100-3)-104²
=100²-9-104²
=(100+104)(100-104)-9
=-4×204-9
=-816-9
=-825
2.2012^2-2013×2011
=2012²-(2012+1)(2012-1)
=2012²-2012²+1
=1