1)-20÷5×1/4+5×(-3)/15
=-4×1/4-1
=-1-1
=-2
2)[1/24÷(-1又1/4)×(-5/6)÷(-3又1/6)]-0.25÷1/4
=1/24×4/5×5/6×(-6/19)-1
=-1/114-1
=-115/114
3)-3×[-5+(1-0.2÷3/5)÷(-2)]
=-3×[-5+2/3÷(-2)]
=-3×[-5-1/3]
=15+1
=16
4)对1,2,3,4可作运算(1+2+3)×4=24,现有有理数3,4,-6,10,请运用加,减,乘,除法则写出三种不同的计算算式,使其结果为24.
(1)3×[(10+4)+(-6)]=24
(2)3×(10-4)-(-6)=24
(3)10-4-3×(-6)=24