Tính hợp lý (nếu có thể):
a) 1125 – ( 374 + 1125) + (-65 +374)
b) -23 . 63 + 23 . 21 – 58 . 23
c) -2003 + (-21+75 + 2003)
d) 942 – 2567 + 2563 – 1942
e) 12 – 12 + 11 + 10 – 9 + 8 – 7 + 5 – 4 + 3 + 2 -1
f/ 210 + [46 + (–210) + (–26)] ;
g) (-8)-[(-5) + 8];
h) 25.134 + 25.(-34)
Ai làm giúp em vs ạ 50 điểm ạ
Tính hợp lý (nếu có thể): a) 1125 – ( 374 + 1125) + (-65 +374) b) -23 . 63 + 23 . 21 – 58 . 23 c) -2003 + (-21+75 + 2003) d) 942 – 2567 + 2563 – 1942
By aikhanh
$\text { Đáp án: }$
` a) ` ` 1125 – (374 + 1125) + (-65 + 374) `
` = 1125 – 374 – 1125 – 65 + 374 `
` = (1125 – 1125) – (374 – 374) – 65 `
` = 0 – 0 – 65 `
` = -65 `
` b) ` ` -23.63+23.21-58.23 `
` = 23.(-63+21-58) `
` = 23.(-100) `
` = -2300 `
` c) ` ` -2003 + (-21 + 75 + 2003) `
` = -2003 – 21 + 75 + 2003 `
` = (-2003 + 2003) – (21 – 75) `
` = 0 – (-54) `
` = 54 `
` d) ` ` 942 – 2567 + 2563 – 1942 `
` = (-1942 + 942) – (2567 – 2563) `
` = -1000 – 4 `
` = -1004 `
` e) ` ` 12 – 12 + 11 + 10 – 9 + 8 – 7 + 5 – 4 + 3 + 2 – 1 `
` = 12 – (12 + 1) + (11 + 2) + (10 + 3) – (9 + 4) + (8 + 5) – 7 `
` = 12 – 13 + 13 + 13 – 13 + 13 – 7 `
` = -1 + 13 + 0 + 13 – 7 `
` = 25 – 7 `
` = 18 `
` f) ` `210 + [46 + (-210) + (-26)] `
` = 210 + 46 – 210 – 26 `
` = (210 – 210) + (46 – 26) `
` = 0 + 20 `
` = 20 `
` g) ` ` (-8) – [(-5) + 8] `
` = -8 + 5 – 8 `
` = (-8 – 8) + 5 `
` = -16 + 5
` = -11 `
` h) ` 25.134 + 25.(-34) `
` = 25.(134 – 34) `
` = 25.100 `
` = 2500 `
a,
$=1125-374-1125-65+374$
$= (1125-1125)+(-374+374)-65$
$= -65$
b,
$=-23.63+23.21-58.23$
$= 23(-63+21-58)$
$= 23.(-100)$
$=-2300$
c,
$=-2003-21+75+2003$
$= -21+75$
$= 54$
d,
$=942-2567+2563-1942$
$= (942-1942)+(2563-2567)$
$= -1000+(-4)$
$= -1004$
e,
$=12-12+11+10-9+8-7+5-4+3+2-1$
$= 11+(10-9)+(8-7)+(5-4)+3+(2-1)$
$= 11+1+1+1+3+1$
$= 18$
f,
$=210+46-210-26$
$= (210-210)+(46-26)$
$= 20$
g,
$=-8+5-8$
$= -16+5$
$= -11$
h,
$=25.134+25.(34)$
$=25(134-34)$
$=25.100$
$=2500$