(3/10)+(-4/11)+(6/5)+(-12/7) (-3.5)+(-3/4)+(-4/3)+(+2/7)+0.75+(-3_数学解答

(3/10)+(-4/11)+(6/5)+(-12/7) (-3.5)+(-3/4)+(-4/3)+(+2/7)+0.75+(-3/7)用简便方法计算实在算不出来了
已知/2a-1/+/5b-4/=0
a的相反数与b的倒数的和
a的绝对值与b的绝对值的和

人气：389 ℃　时间：2020-03-09 14:12:20

解答

(3/10)+(-4/11)+(6/5)+(-12/7)
=3/10-4/11+6/5-12/7
=(3/10+6/5)-(4/11+12/7)
=3/2-160/77
=-89/154
2.(-3.5)+(-3/4)+(-4/3)+(+2/7)+0.75+(-3/7)
=-3.5+(-3/4+0.75)+(2/7-3/7)-4/3
=-3.5+0-1/7-4/3
=-(7/2+1/7+4/3)
=-(147+6+56)/42
=-209/42