1.tính:
a) A= \(2^3\).\(5^3-3\).{639-8(\(7^8\):\(7^6\)+1)}
b) B= \(-19^2 \)-{147-2[\(7^3\)+(93-126):(6-\(3^2\))]}
1:Tính :
a,1/2+7/8+7/19+42/47 b,3/2+6/5+17/8+36/27 c,3/5+(2/8+2/5+6/8) d,5 3/7+(2 5/21-1 2/3)
Tính nhanh nếu có thể: b)B=5/2 + 6/-11 + 3/8 - 7/2 + 6/8 + -5/11 c)C=4/3 + 3/5 +7/3 + 2/5 - -1/3 d)D=-5/6 . 4/19 + -7/12 . 4/19 - 40/57 e)E=1/3 . 4/5 + 1/-3 . 9/5 + 2/3
b: \(B=\dfrac{5}{2}-\dfrac{7}{2}+\dfrac{3}{8}+\dfrac{6}{8}+\dfrac{-6}{11}-\dfrac{5}{11}=-2-1+\dfrac{9}{8}=\dfrac{9}{8}-3=-\dfrac{15}{8}\)
c: \(C=\left(\dfrac{4}{3}+\dfrac{7}{3}+\dfrac{1}{3}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=4+1=5\)
d: \(D=\dfrac{4}{19}\left(\dfrac{-5}{6}-\dfrac{7}{12}\right)-\dfrac{40}{57}\)
\(=\dfrac{4}{19}\cdot\dfrac{-17}{12}-\dfrac{40}{57}=-1\)
e: \(E=\dfrac{1}{3}\left(\dfrac{4}{5}-\dfrac{9}{5}\right)+\dfrac{2}{3}=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)
(-9).27-13.9+40.11
= (-243) - 117+440
= 80+440
= 520
-192-{147-2[73+(93-126):(6-32)]}
= 361- {147- 2[ 343 +(-33):(-3)]}
= 361- { 147-2[ 343+ 11]}
=361 - { 147 -2. 354}
=361 - { 147- 708}
= 361 - (-561)
= 922
2. Tính: A) 1/3 + 1/5 - 1/4. B) 7/8 - ( 1/4 + 2/5 ). C) 5/11 - ( 3/5 - 6/11 ). D) 5/7 - ( 19/35 - 6/15 ).
`A) 1/3 + 1/5 - 1/4 = 20/60 + 12/60 - 15/60 = 17/60`
` B) 7/8 - ( 1/4 + 2/5 ) = 7/8 - 2/4 -2/5 = 5/8-2/8 = 9/40`
` C) 5/11 - ( 3/5 - 6/11 ) = 5/11 - 3/55 = 25/55 - 3/55 = 22/55=2/5 `
` D) 5/7 - ( 19/35 - 6/15 ) = 5/7 - 1/7 = 4/7 `
2. Tính: A) 1/3 + 1/5 - 1/4. B) 7/8 - ( 1/4 + 2/5 ). C) 5/11 - ( 3/5 - 6/11 ). D) 5/7 - ( 19/35 - 6/15 ).
`1/3 + 1/5 -1/4`
`= 5/15 + 3/15 -1/4`
`= 8/15 -1/4`
`= 17/60`
__
`7/8 -(1/4 + 2/5)`
`= 7/8-1/4 - 2/5`
`= 7/8 - 2/8 -2/5`
`= 5/8 -2/5`
`= 9/40`
__
`5/11-(3/5 -6/11)`
`= 5/11 -3/5 +6/11`
`= (5/11 + 6/11)-3/5`
`= 1 -3/5`
`= 5/5-3/5`
`=2/5`
__
`5/7 - ( 19/35 - 6/15)`
`= 5/7 - 19/35 + 6/15`
`= 25/35 -19/35 + 6/15`
`=6/35 +6/15`
`=4/7`
Tính bằng cách hợp lý:
\(a,\dfrac{2}{3}+\left(\dfrac{5}{7}+\dfrac{-2}{3}\right)\)
\(b,\left(\dfrac{-1}{4}+\dfrac{5}{8}\right)+\dfrac{-3}{8}\)
\(c,\dfrac{7}{5}.\dfrac{8}{19}+\dfrac{7}{5}.\dfrac{12}{19}-\dfrac{7}{5}.\dfrac{1}{19}\)
\(d,6\dfrac{3}{10}-\left(3\dfrac{4}{7}+2\dfrac{3}{10}\right)\)
\(e,\left(31,12-5,97\right)-\left(-68,88+4,03\right)\)
\(h,3,7.\left(-10,56\right)+3,7.110,56\)
Bài 1: Tính
a) 1/3 + 1/5 - 1/4 b) 7/8 - ( 1/4 + 2/5 ) c) 5/11 - ( 3/5 - 6/11 )
Bài 2: Tìm x
a) x + 2/5 = 1/2 b) x + 3/7 = 2/5 + 3/10 c) 19/20 - x = 8/5 - 3/4
Bài 3: Tìm số tự nhiên x, biết:
a ) 4/7 < x < 1/2 + 10/3 b) 3/10 + 8/5 < x < 2/5 + 5
Giúp mình nha ^^ Ai nhanh mình Tick !!!!!!!!!❤❤
Bài 1 . Tính nhanh :
A = 6/7 + 1/7 . 2/7 + 1/7 . 5/7
B = 4/9 . 13/3 - 4/3 . 40/9
M = 8/3 . 2/5 . 3/8 . 10 . 19/2
N = 5/7 . 5/11 + 5/7 . 2/11 - 5/7 . 14/11
B=4*13/9*3-4/3*40/9
B=4/3*13/9-4/3*40/9
B=4/3*(13/9-40/9)
B=4/3*(-27)/9
B=4*(-3)/9
B=-4
A=6/7 + 1/7.(2/7+5/7)
A=6/7 + 1/7.7/7=6/7+1/7.1
A=6/7+1/7=7/7=1
M=8/3*2/5*3/8*10*19/2
M=(8/3*3/8)*(2/5*10)*19/2
M=1*4*19/2
M=28
1) Tính
a) 1-2-3+4+5-6-7+8+.......+17-18-19+20
b)1+2+3-4-5+6+7-8-........-97+98+99-100
a) 1-2-3+4+5-6-7+8+......+17-18-19+20=(1-2-3+4)+(5-6-7+8)+....+(17-18-19+20)
=0+0+......+0
=0
câu b hơi khó mình cần thời gian ,mai mình đưa kết quả cho