Câu hỏi : ( 198 x 2 ) - 15 =
( 12 - 8 ) x 7 =
Câu a7/8 chia đóng ngoặc 2/9 - 18 đóng ngoặc + 7/8 x 1/36 - 5/12 câu b 3/7 x 4/9 + 3/7 x 5/9 chia 6/12 câu c 5^8 x 16/31 - 5^8 x 47/31 + 1/3 câu d 7/2 x 3/8 + 7/2 x 5/8 chia 4/15
a: =7/8:(2/9-18+1/36)-5/12
=-7/142-5/12=-397/852
b: =3/7(4/9+5/9:6/12)=2/3
c: =5^8(16/31-47/31)+1/3=-5^8+1/3
d: =7/2(3/8+5/8:4/15)=609/64
Tìm x:
( 7 x X ) x 8 - 2 x ( 7 - X ) = 6
Tính nhanh:
4 x 13 + 12 x 96 -4
( 4 + 8 + 12 +...+400 ) : ( 200 + 198 +...+ 4 x 2 )
Tìm x:
( 7 x X ) x 8 - 2 x ( 7 - X ) = 6
Tính nhanh:
4 x 13 + 12 x 96 -4
Bài 2: Thực hiện phép tính ( hợp lý nếu có thể)
a) 12 x 18 + 14 x 3 - 255 : 17
b) 68 + 42 x 5 - ( 198 : 11 - 8 )
c) 13 + 21 x 5 - ( 198 : 11 - 8 )
d) 18 - 4 x (27 - 90 + 73)
e) 15 x ( 27 + 18 +6 ) + 15 x (23+12)
f) 417 + 235 + 583 + 765
g) 5 + 8 + 11 + 14 + … + 38 + 41
a) 12 x 18 + 14 x 3 - 255 : 17
= 216 + 42 - 15
= 243
b) 68 + 42 x 5 - (198 : 11 - 8)
= 68 + 210 - (18 - 8)
= 68 + 210 - 10
= 268
c) 13 + 21 x 5 - (198 : 11 - 8)
= 13 + 105 - (18 - 8)
= 13 + 105 - 10
= 108
Câu 13 : (-1/4 + 5/8 ) + -3/5
Câu 14 : M = 5/9 x 7/13 + 5/9 x 9/13 - 5/9 x 3/13
câu 15 : E = (-3/4 + 2/5) : 3/7 + (3/5 + -1/4) : 3/7
Câu 16 : H = 7/8 : (2/9 - 1/8) + 7/8 : (1/36 - 5/12)
Câu 13 :
\(\left(-\frac{1}{4}+\frac{5}{8}\right)+-\frac{3}{5}\)
\(=\frac{3}{8}-\frac{-3}{5}\)
\(=\frac{39}{40}\)
Câu 14 :
\(M=\frac{5}{9}.\frac{7}{13}+\frac{5}{9}.\frac{9}{13}-\frac{5}{9}.\frac{3}{13}\)
\(=\frac{5}{9}.\left(\frac{7}{13}+\frac{9}{13}-\frac{3}{13}\right)\)
\(=\frac{5}{9}.1=\frac{5}{9}\)
Câu 15 :
\(E=\left(-\frac{3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)
\(E=\left(-\frac{3}{4}+\frac{2}{5}+\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)
\(E=0\)
Câu 16 :
\(H=\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{8}\right)+\frac{7}{8}:\left(\frac{1}{36}-\frac{5}{12}\right)\)
\(=\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{8}+\frac{1}{36}-\frac{5}{12}\right)\)
\(=\frac{7}{8}:\frac{-7}{24}=-3\)
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Câu 14:
M = \(\frac{5}{9}\) \(.\) \(\frac{7}{13}\) \(+\) \(\frac{5}{9}\) \(.\) \(\frac{9}{13}\) \(-\) \(\frac{5}{9}\) \(.\) \(\frac{3}{13}\)
M = \(\frac{5}{9}\) \(.\) ( \(\frac{7}{13}\)\(+\) \(\frac{9}{13}\) \(-\) \(\frac{3}{13}\))
M = \(\frac{5}{9}\) \(.\) \(1\)
M = \(\frac{5}{9}\)
Câu 1:
30.45+55.30–30.30
5√2.2√2–1+135
15+(-3)+|-111+(-10)|-3|
15–{200:[ 30+( 16+2√15 : 2√12 )]}
Câu 2:
x –20= -36
( 5x – 25 ) : 4 + 75 = 125
| x – 4 | = 9
( 3x – 17 ) . 16 = 64
5x –18 = -3
2 . | x | –5 = 3
x – 5 = ( -14 ) + 8
| 2x – 7 | – | -3/2 | = 7
Câu 3:
21 . 16 + 21 . 59 + 21 . 35
80 – ( 4 . 25 – 3 . 8 )
( -12 ) + 83 + ( -48 ) + 17
| ( -12 ) + ( -7 ) | . 2 – 30
8 . ( -7 ) + ( +3 ) . 8
| -5 | + | 16 | + | 5 |
Câu 1:Tính
a.7/13 x 7/15 - 5/12 x 21/39 + 49/91 x 8/15
b. (12/199 + 23/200 - 34/201) x (1/2 - 1/3 - 1/6)
Câu 2 :Tìm x bt:
1. 0,5 + ( X - 15/2 ) : 1/2 = 9/2
2. 2012 x X - 2010 x X = 2014
3. ( X+ 1) + ( X + 2) + ( X + 3 ) + .....+ ( X + 100 ) =5750
Ai nhanh mk tik.Thanks nhìu
a) \(\frac{7}{13}x\frac{7}{15}-\frac{5}{12}x\frac{21}{39}+\frac{49}{91}x\frac{8}{15}=\frac{7}{13}x\frac{7}{15}-\frac{5}{12}x\frac{7}{13}+\frac{7}{13}x\frac{8}{15}\)
\(=\frac{7}{13}x\left(\frac{7}{15}-\frac{5}{12}+\frac{8}{15}\right)=\frac{7}{13}x\left(1-\frac{5}{12}\right)=\frac{7}{13}x\frac{7}{12}=\frac{49}{156}\)
b) \(\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)x\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)=\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)x0=0\)
Bài 2:
a) \(0,5+\left(x-\frac{15}{2}\right):\frac{1}{2}=\frac{9}{2}\)
\(\left(x-\frac{15}{2}\right):\frac{1}{2}=4\)
\(x-\frac{15}{2}=2\)
x = 19/2
b) \(2012\times x-2010\times x=2014\)
\(x\times\left(2012-2010\right)=2014\)
\(x\times2=2014\)
x = 1007
c) ( x + 1) + (x+2) + (x+3)+...+(x+100) = 5750
\(x\times100+\left(1+2+3+...+100\right)=5750\)
\(x\times100+5050=5750\)
\(x\times100=700\)
x = 7
Câu 3:
a)7/4 - 11/8 +1/2
b)3/16 + 7/30 x 40/64
c)(9/2 - 15/4):21/12
\(a,\dfrac{7}{8}:b,\dfrac{1}{3}c;\dfrac{3}{7}\)
Câu 1: Tìm x,y,z biết 2x/3=3y/4=4z/5 và x-2y+3z=-31
Câu 2: Tìm x biết x-6/7+x-7/8+x-8/9=x-9/10+x-10/11+x-11/12
Câu 3: A =1/15+1/16+1/17+...+1/44
CMR: A>5/6
Tính bằng cách thuận tiện nhất :
a) 60 x ( 7/12 + 4/15 )
b) 1/2 x 2/3 x 3/4 x 4/5 x 5/6 x 6/7 x 7/8 x 8/9
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