简便计算:4⼀5-4⼀5X5⼀6,3⼀7X3⼀21X21X7,4⼀15X2⼀19+17⼀19X4⼀

简便计算:4/5-4/5X5/6,3/7X3/21X21X7,4/15X2/19+17/19X4/19
2025-06-22 04:49:22
推荐回答(3个)
回答1:

4/5-4/5X5/6
=(1-5/6)X4/5
=1/6X4/5
=2/15
3/7X3/21X21X7
=3/7x7×(3/21×21)
=3×3
=9
4/15X2/19+17/19X4/15
=4/15X(2/19+17/19)
=4/15X1
=4/15

回答2:

4/5-4/5X5/6

=4/5×(1-5/6)
=4/5×1/6
=2/15

3/7X3/21X21X7
=(3/7×7)×(3/21×21)
=3×3
=9

4/15X2/19+17/19X4/19没有简便方法,是不是抄错题了?

回答3:

①=4/5*(1-5/6)=4/5*1/6=2/15
②=3/7*7*(3/21*21)=3*3=9
③=4/19*(2/15+17/19)