B , ( 2/15 + 3/40 + 4/96 + 5/204 + 6/391 ) *x ( x-1) =20/69
A , ( 1/4 + 1/28 + 1/70 + ...... + 1/8554 ) *x = 31/94
Những câu hỏi liên quan
( 2/15 + 3/40 + 4/96 + 5/204 + 6/391 ) *x ( x-1) =20/69
(2/ 3. 5 + 3/ 5. 8 + 4/ 8. 12 + 5/ 12. 17+ 6/ 17. 23). x(x- 1)= 20/ 69
(1/ 3-1/ 5 + 1/ 5-1/ 8 + 1/ 8-1/ 12 + 1/ 12-1/ 17+ 1/ 17-1/ 23). x(x- 1)= 20/ 69
(1/ 3-1/ 23). x(x- 1)= 20/ 69
mk làm đến đâu còn lại bạn tự làm nha
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( \(\frac{1}{4}\)+ \(\frac{1}{28}+\frac{1}{70}+.....+\frac{1}{8554}\)) *x =\(\frac{31}{94}\)
Mình lười chép lại đề nên làm lun nha
3 * (1/4 + 1/28 + 1/70 +...+1/8554) * x = 31/94 * 3
(3/4 + 3/28 + 3/70 + ... +3/8554) * x = 93/94
(3/1*4 + 3/4*7 + 3/7*10 + ... + 3/ 91*94) * x = 93/94
(1/1 - 1/94) * x = 93/94
93/94 * x = 93/94
=> x = 93/94 : 93/94 = 1
Vậy x=1
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1/6 + 2/15 + 3/40 + 4/96 + 5/204 + 6/391 + 7/690
Gấp
=1/2x3+2/3x5+3/5x8+4/8x12+5/12x17+6/17x23+7/23x30
=1/2-1/3+1/3-1/5+...+1/23-1/30
=1/2-1/30
=7/15
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Thực hiện phép tính:
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
C) ( -2/3 + 3/7 ) : 4/5 + (-1/3 + 4/7 ) : 4/5
D) 5/9 : ( 1/11 -5/22 ) + 5/9 : ( 1/15 - 2/3 )
E) 3/14 : 1/28 -13/21 : 1/28 + 29/42 : 1/28 - 8
F) ( -40/51 x 0,32 x17/20) : 64/75
Đây là dấu x ( là nhân ) mọi người nhé
mong mn giúp em ạ
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
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Tính nhanh : A= \(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{4}{96}+\frac{5}{204}+\frac{6}{391}+\frac{7}{690}+\frac{8}{1140}+\frac{9}{1786}\)
\(A=\frac{3-2}{2\times3}+\frac{5-3}{3\times5}+\frac{8-5}{5\times8}+...\frac{38-30}{30\times38}+\frac{47-38}{38\times47}\)
\(A=\frac{3}{2\times3}-\frac{2}{2\times3}+\frac{5}{3\times5}-\frac{3}{3\times5}+...\frac{38}{30\times38}-\frac{30}{30\times38}+\frac{47}{38\times47}-\frac{38}{38\times47}\)
\(A=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}+...+\frac{1}{30}-\frac{1}{38}+\frac{1}{38}-\frac{1}{47}\)
\(A=\frac{1}{2}-\frac{1}{47}=\frac{47}{94}-\frac{2}{94}=\frac{45}{94}\)
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a x 4 2,7 22,7 b 49.8 x 2,4 29,8 c 1 7 2 5 x 3 7 d x 4 x 15 1919 e x 0,7 x 0,2 28 f x 3 5 x 2 7 31 70
Xem chi tiết
a x 4 2,7 22,7 b 49.8 x 2,4 29,8 c 1 7 2 5 x 3 7 d x 4 x 15 1919 e x 0,7 x 0,2 28 f x 3 5 x 2 7 31 70
Xem chi tiết
1) 2³ .x -5² x = 2( 5² + 2² ) -33. 2) 15÷ ( x +2) = (3³ +3) ÷1
3) 20÷ (x +1) = (5² +1 ) ÷13. 4) 320÷ ( x -1 ) = (5³ - 5² ) ÷4 +15
5) 240 ÷ ( x -5 ) = 2² .5² -20. 6) 70 ÷ ( x -3) = ( 3⁴ -1) ÷ 4 - 10
Giúp mình với mình Tối nay mình đi học rồi
1) \(2^3\times x-5^2\times x=2\times\left(5^2+2^2\right)-33\)
\(x\times\left(2^3-5^2\right)=2\times\left(25+4\right)-33\)
\(x\times\left(8-25\right)=2\times29-33\)
\(x\times-17=25\)
\(x=-\dfrac{25}{17}\)
2) \(15\div\left(x+2\right)=\left(3^3+3\right)\div1\)
\(15\div\left(x+2\right)=\left(27+3\right)\div1\)
\(15\div\left(x+2\right)=30\div1\)
\(15\div\left(x+2\right)=30\)
\(x+2=\dfrac{1}{2}\)
\(x=-\dfrac{3}{2}\)
3) \(20\div\left(x+1\right)=\left(5^2+1\right)\div13\)
\(20\div\left(x+1\right)=\left(25+1\right)\div13\)
\(20\div\left(x+1\right)=26\div13\)
\(20\div\left(x+1\right)=2\)
\(x+1=20\div2\)
\(x+1=10\)
\(x=9\)
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4) \(320\div\left(x-1\right)=\left(5^3-5^2\right)\div4+15\)
\(320\div\left(x-1\right)=\left(125-25\right)\div4+15\)
\(320\div\left(x-1\right)=100\div4+15\)
\(320\div\left(x-1\right)=25+15\)
\(320\div\left(x-1\right)=40\)
\(x-1=8\)
\(x=9\)
5) \(240\div\left(x-5\right)=2^2\times5^2-20\)
\(240\div\left(x-5\right)=4\times25-20\)
\(240\div\left(x-5\right)=100-20\)
\(240\div\left(x-5\right)=80\)
\(x-5=30\)
\(x=35\)
6) \(70\div\left(x-3\right)=\left(3^4-1\right)\div4-10\)
\(70\div\left(x-3\right)=\left(81-1\right)\div4-10\)
\(70\div\left(x-3\right)=80\div4-10\)
\(70\div\left(x-3\right)=20-10\)
\(70\div\left(x-3\right)=10\)
\(x-3=7\)
\(x=10\)
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tìm x thuộc Z
a) 1/3 + (-2)/5 + 1/6 + (-1)/5 < x < ( -3)/4 + 2/7 + (-1)/4 + 3/5 + 5/7
b) 5/17 + (-4)/9 + (-20)/31 + 12/17 + (-11)/31 < x/9 < (-3)/7 + 7/15 + 4/(-7) + 8/15 +2/3