Đáp án:
Giải thích các bước giải:
bài 1:
a.M=40/31.39+35/39.46+30/46.52+25/52.57
M=5(8/31.39+7/39.46+6/46.52+5/52.57)
M=5(1/31.39+1/39.46+1/46.52+1/52.57)
M=5(1/31-1/39+1/39-1/46+1/46-1/52+1/52-1/57)
M=5(1/31-1/57)
M=5.26/1767
M=130/1767
b.N=1/14.15-1/15.16+1/16.17+1/17.18
N=1/14-1/15-1/15-1/16+1/16-1/17+1/17-1/18
N=1/14-1/18
N=1/63
bài 2:
a.2011.x+(1+2+....+2010)=2029099
2011.x+2021055=2029099
2011.x=2029099-2021055
2011.x=8044
x=8044:2011
x=4