跪求七年级下册数学（北京师范大学出版社）的课本答案
2个回答
解:(1)原式=m^2-3m+2-4m+2n+1
=m^2-3m-4m+2n+2+1
=m^2-7m+2n+3
(2)原式=3x^2+4x-1-3x^2-9x
= 3x^2-3x^2 +4x-9x-1
=-5x-1
(3)原式=-5x^2+15-6x^2-10
=-5x^2-6x^2+15-10
=-11x^2+5
(4)原式=-x^2y-3xy+4+3x^2y-3xy+6
=-x^2y+3x^2y-3xy-3xy+4+6
=2x^2y-6xy+10
(5)原式=11/2x^2-29x+10y-5/2x^2+13x-24y
=11/2x^2-5/2x^2-29x+13x+10y-24y
=3x^2-13x-14y
(6)原式=-1/2k^3-k^2+7+1/2k^3-k^2+2k
=-1/2k^3+1/2k^3-k^2-k^2+2k+7
=-2k^2+2k+7
2.(1) (180`-15`)(3+1+1)=33`
(2) 第一个角.33`*3=99` 第二个角.33`+15`=48`
