已知2m-n=3,4m+3n=1,求5n(2m-n)²-2(n-2m)³的值

来源:学生作业学帮网 编辑:学帮网 时间:2024/05/29 13:33:04

已知2m-n=3,4m+3n=1,求5n(2m-n)²-2(n-2m)³的值

=5n(2m-n)²+2(2m-n)³
=(2m-n)²(5n+4m-2n)
=(2m-n)²(4m+3n)
=3²*1
=9

5n(2m-n)²-2(n-2m)³
=5n(2m-n)²-(-1)³*2*(2m-n)³
=(2m-n)²(5n+4m-2n)
=(2m-n)²(4m+3n)
=3²*1
=9

原式=5n(2m-n)^2+2(2m-n)^3 提出公因式 (2m-n)^2
=(2m-n)^2×(5n+4m-2n)
=(2m-n)^2×(4m+3n)
代入 =9×1=9

5n(2m-n)²-2(n-2m)³
=5n(2m-n)²-(-1)³*2*(2m-n)³
=(2m-n)²(5n+4m-2n)
=(2m-n)²(4m+3n)
=3²*1
=9