Tính nhanh: a) – (– 2012 + 789) + (– 211) + (– 1012 – 1789). b) – 72 . 17 + 72 . 31 – 72 . 114. c) 512 . (2 – 128) – 128 . (– 512).. d) 120 . (5 – 117) – 117 . (– 120)
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23/06/2024
Tính nhanh:
a) – (– 2012 + 789) + (– 211) + (– 1012 – 1789).
b) – 72 . 17 + 72 . 31 – 72 . 114.
c) 512 . (2 – 128) – 128 . (– 512)..
d) 120 . (5 – 117) – 117 . (– 120)
Trả lời
Lời giải
a) – (– 2012 + 789) + (– 211) + (– 1012 – 1789)
= 2012 – 789 – 211 – 1012 – 1789
= ( 2012 – 1012 ) – 789 – 1789 – 211
= 1000 – 211 – 789 – 1789
= 789 – 789 – 1789
= 0 – 1789
= – 1789.
b) – 72 . 17 + 72 . 31 – 72 . 114
= – 72 . (17 + 114 – 31)
= – 72 . (131 – 31)
= – 72 . 100
= – 7200.
c) 512 . (2 – 128) – 128 . (– 512)
= 512 . 2 – 512 . 128 + 128 . 512
= 512 . 2 + 0
= 1024.
d) 120 . (5 – 117) – 117 . (– 120)
= 120 . 5 – 120 . 117 + 117 . 120
= 120 . 5 – 0
= 600.
