tính nhanh nếu có thể :
a) 2155 – ( 174 + 2155 ) + ( -68 + 174 )
b) -25.72 + 25.21 – 49.25
c) 25.21 + 25.72 + 49.25
d) 27 ( 13 – 16 ) – 16 ( 13 – 27 )
e) -1911 – ( 1234 – 1911 )
f) 156 . 72 + 28 .156
g) 32. ( -39 ) + 16 . ( -22 )
h) -1945 – ( 567 – 1945 )
i) 184 . 33 + 67 . 184
k) 44 . ( -36 ) + 22 . ( -28 )
Đáp án:
????
Giải thích các bước giải:
a) 2155 – ( 174 + 2155 ) + ( -68 + 174 )
= 2155 – 174 – 2155 + (-68) + 174
= (2155 – 2155) – (174 – 174) + (-68)
= 0 + 0 + (-68)
= -68
b) -25 . 72 + 25 . 21 – 49 . 25
= 25 . (-72) + 25 . 21 – 49 . 25
= 25 . (-72 + 21 – 49)
= 25 . (-100)
= -2500
c) 25 . 21 + 25 . 72 + 49 . 25
= 25 . (21 + 72 + 49)
= 25 . 142
= 3550
d) 27 ( 13 – 16 ) – 16 ( 13 – 27 )
=27 . 13 – 27 . 16 – 16 . 13 + 16 . 27
=(27 – 16) . 13
=11 . 13
=143
e) -1911 – ( 1234 – 1911 )
= -1911 – 1234 + 1911
= (-1911 + 1911) – 1234
= 0 – 1234
= -1234
f) 156 . 72 + 28 . 156
= 156 . (72 + 28)
= 156 . 100
= 15600
g) 32 . (-39) + 16 . (-22)
= 16 . 2 . (−39) + 16 . (−22)
= 16 . (−78) + 16 . (−22)
= 16 . [ (−78) + (−22) ]
= 16 . (−100)
= −1600
h) -1945 – ( 567 – 1945 )
= – 1945 – 567 + 1945
= (-1945 + 1945) – 567
= 0 – 567
= -567
i) 184 . 33 + 67 . 184
= 184 . (33 + 67)
= 184 . 100
= 18400
k) 44 . ( -36 ) + 22 . ( -28 )
= 44 . 2 (−18) + 22 . 4 . (−7)
= 88 . (−18) + 88 (−7)
= 88 (−18 −7)
= 88 . (−25)
= −2200
Chúc bạn vui vẻ!@milesuni3001
(cho mk ctlhn nha^^)
Đáp án:
Giải thích các bước giải:
` a) 2155 – ( 174 + 2155 ) + ( -68 + 174 ) `
` 2155 – 174 + 2155 + -68 + 174 `
`( 2155 – 2155 ) + 174 + 174 + – 68 `
` 0 + 280 `
` 280 `
` b) -25.72 + 25.21 – 49.25 `
` -1800 + 525 – 1225 `
` – 2500 `
` c) 25.21 + 25.72 + 49.25 `
` 525 + – 1800 + – 1225 `
` – 2500 `
` d) 27 ( 13 – 16 ) – 16 ( 13 – 27 ) `
` 27 . 13 – 16 – 16 . 13 – 27 `
` 27 . ( 13 – 16 – 16 – 13 ) `
` 27 . – 32 `
` – 864 `
` e) -1911 – ( 1234 – 1911 ) `
` – 1911 – 1234 + 1911 `
` ( – 1911 + 1911 ) – 1234 `
` 0 – 1234 `
` – 1234 `
` f) 156 . 72 + 28 .156 `
` 156 . ( 72 + 28 ) `
` 156 . 100 `
` 15600 `
` g) 32. ( -39 ) + 16 . ( -22 ) `
` ( 32 + – 22 ) . – 39 + 16 `
` 10 . – 39 + 16 `
` – 390 + 16 `
` – 384 `
` h) -1945 – ( 567 – 1945 ) `
` – 1945 – 567 + 1945 `
` ( -1945 + 1945 ) – 567 `
` – 567 `
` i) 184 . 33 + 67 . 184 `
` 184 . ( 33 + 67 ) `
` 184 . 100 `
` 18400 `
` k) 44 . ( -36 ) + 22 . ( -28 ) `
` – 1584 + -616 `
` – 2200 `