1题:
原式=(-13/2)×2/3-1/2×2/7+1/3×(-13/2)-5/7×1/2
=(-13/2)×(2/3+1/3)-1/2×(2/7+5/7)
=(-13/2)×1-1/2×1
=-13/2-1/2
=-(13/2+1/2)
=-7
2题
原式=(-1/42)÷(1/6-2/7+2/3-3/14)
=(-1/42)÷[(1/6+2/3)-(2/7+3/14)]
=(-1/42)÷(5/6-1/2)
=(-1/42)÷1/3
=(-1/42)×3
=-1/14
1题:
原式=(-13/2)×2/3-1/2×2/7+1/3×(-13/2)-5/7×1/2
=(-13/2)×(2/3+1/3)-1/2×(2/7+5/7)
=(-13/2)×1-1/2×1
=-13/2-1/2
=-(13/2+1/2)
=-7
2题
原式=(-1/42)÷(1/6-2/7+2/3-3/14)
=(-1/42)÷[(1/6+2/3)-(2/7+3/14)]
=(-1/42)÷(5/6-1/2)
=(-1/42)÷1/3
=(-1/42)×3
=-1/14