Question

简算下列题目

999.3-998.2+997.3-996.2+···+3.3-2.2+1.3-0.2
(1+1/2)*(1+1/4)*(1+1/6)···*(1+1/10）*（1-1/3）*（1-1/5）*···*（1-1/9）
5.65*0.875+9/8*5.35-0.875*0.9
2/5*[2.6+3/4-(0.65+3/4)]/3/4
明天要，速度！！！！！！！！！！！！！！！15是我全部的分了，希望大家谅解

Answer 1

999.3-998.2+997.3-996.2+···+3.3-2.2+1.3-0.2
=(999.3-998.2)+(997.3-996.2)+……+(3.3-2.2)+(1.3-0.2)
=1.1+1.1+……+1.1+1.1
=1.1x500
=550

(1+1/2)*(1+1/4)*(1+1/6)···*(1+1/10）*（1-1/3）*（1-1/5）*···*（1-1/9）
(1+1/2)x(1-1/3)=1
(1+1/4)x(1-1/5)=1
(1+1/2)x(1+1/4)x(1+1/6)x...x(1+1/10)x(1-1/3)x(1-1/5)x..x(1-1/9)=1

5.65*0.875+9/8*5.35-0.875*0.9
=5.65*0.875+1.125*5.35-0.875*0.9
=5.65*0.875-0.875*0.9+1.125*5.35
=0.875*（5.65-0.9）+0.875*5.35+0.25*5.35
=0.875*4.75+（4.75*1.125+0.6*1.125）
=4.75*（0.875+1.125）+0.6*1.125
=4.75*2+0.6*1.125
=19/4*2+6/10*9/8
=9.5+0.625
=10.125

2/5*[2.6+3/4-(0.65+3/4)]/3/4
=2/5*[2.6+0.75-(0.65+0.75)]/3/4
=2/5*(3.35-1.4)/3/4
=2/5*1.95/3/4
=2/5*39/20÷3/4
=26/25

Answer 2

(1+1/2)*(1+1/4)*(1+1/6)···*(1+1/10）*（1-1/3）*（1-1/5）*···*（1-1/9）
=(1+1/2)x(1-1/3)x(1+1/4)x(1-1/5)x(1+1/6)x,,,,,x(1+1/10)
=3/2x 2/3x 5/4 x4/5 x7/6 x6/7 x9/8x8/9 x11/10
=1x1x1x.... x11/10
=11/10

Answer 3

440
1
10.175
1.04