计算:(1)(-25)+34+156+(-65)(2)23-17-(-7)+(-16)(3)(-26.54)-(-6.4)+18.54-6.4 ..
计算:(1)(-25)+34+156+(-65)(2)23-17-(-7)+(-16)(3)(-26.54)-(-6.4)+18.54-6.4(4)(?0.5)?(?31...
计算:(1)(-25)+34+156+(-65)(2)23-17-(-7)+(-16)(3)(-26.54)-(-6.4)+18.54-6.4 (4)(?0.5)?(?314)+2.75?(+712)(5)1-2+3-4+5-6+…+79-80+81.
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(1)(-25)+34+156+(-65),
=-90+190,
=100;
(2)23-17-(-7)+(-16),
=23-17+7-16,
=30-33,
=-3;
(3)(-26.54)-(-6.4)+18.54-6.4,
=-26.54+6.4+18.54-6.4,
=-26.54+18.54+6.4-6.4,
=-8;
(4)(-0.5)-(-3
)+2.75-(+7
),
=-0.5+3
+2.75-7
,
=6-8,
=-2;
(5)1-2+3-4+5-6+…+79-80+81,
=(1-2)+(3-4)+(5-6)+…+(79-80)+81,
=-1-1-1-…-1+81,
=-40+81,
=41.
=-90+190,
=100;
(2)23-17-(-7)+(-16),
=23-17+7-16,
=30-33,
=-3;
(3)(-26.54)-(-6.4)+18.54-6.4,
=-26.54+6.4+18.54-6.4,
=-26.54+18.54+6.4-6.4,
=-8;
(4)(-0.5)-(-3
1 |
4 |
1 |
2 |
=-0.5+3
1 |
4 |
1 |
2 |
=6-8,
=-2;
(5)1-2+3-4+5-6+…+79-80+81,
=(1-2)+(3-4)+(5-6)+…+(79-80)+81,
=-1-1-1-…-1+81,
=-40+81,
=41.
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