tính
1 /1/2 x 1 1/3 x 1/4 ....1 1/2017
[ 1 - 1/5 ] x [ 1 - 1/6 ] x [ 1 - 1/7 ] x [ 1 -1/8 ] x [ 1 - 1/9 ]
1 1/3 x 1 1/8 x 1 1/15 ....1 1/9800
Bài 299: Tính
1) 1/3 x 1/2 x 3/7
2) 5/4 x 1/3 + 1/7
3) 8 x ( 8/9-2/3 )
4) 5/6 x 48/20 x 1/2
5) ( 2/5 + 3/4 ) x 8
6) 10 x ( 1/2-1/5 )
Trình bày rõ cách làm giúp nhen!!
1: \(=\dfrac{1}{3}\cdot\dfrac{3}{7}\cdot\dfrac{1}{2}=\dfrac{1}{7\cdot2}=\dfrac{1}{14}\)
2: =5/12+1/7
=35/84+12/84=47/84
3: =8(8/9-6/9)
=8*2/9=16/9
4: \(=\dfrac{5}{12}\cdot\dfrac{12}{5}=1\)
5: =16/5+6
=16/5+30/5=46/5
6: =10*1/2-10*1/5
=5-2=3
BÀI 1 RÚT GỌN PHÂN SỐ
108 /-180 B/ 200/ 280 C/ -23232323/ 46464646
BÀI 2 TÍNH
A= 2/ 2.3 + 2/ 3.4 + 2/ 4.5 + ........ + 2/ 99.100
B= 1/3 + 1/ 3.5 + 1/ 5.7 + ........+ 1/ 2013 .2015 + 1/ 2015 .2017
C= 1/12 + 1/20 +1/ 30 + .....+ 1/ 506 +1/ 552
D= 3/4 . 8/9 . 15/16 . 24. 25.........9800/9801
BÀI 3: TÌM X
A/ 3/ X+2= 1/6 B/ -7/ X= 3/15 C/ X- 11/8 = 5/4X
BÀI 4:
( 2015/ 2016 + 2016 + 2017 + 2017/ 2018 ). ( 1/2- 1/3- 1/6)
HÃY GIẢI GIÚP MÌNH NHANH NHA
1) 1/3 x 1/2 x 3/7 2) 5/4 x 1/3 + 1/7 3) 8 x ( 8/9-2/3 ) 4) 5/6 x 48/20 x 1/2 5) ( 2/5 + 3/4 ) x 8 6) 10 x ( 1/2-1/5 )
1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14
2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84
3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1
5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5
6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3
tìm x biết
1) x=-1/2 + 3/4 2) x - 1/5 = 2/11 3) x - 5/6 = 16/42 + -8/56
4) x/5 = 5/6 + -19/30 5) |x| - 1/4 = 6/18 6)x = -1/2 +3/4
7) x/15 = 3/5 + -2/3 8)11/8 + 13/6 = 85/x 9) x - 7/8 = 13/12
10) x - -6/15 = 4/27 11) -\(\dfrac{-6}{12}\)+ x = 9/48 12) x - 4/6 = 5/25 + -7/15
1: x=3/4-1/2=3/4-2/4=1/4
2: x-1/5=2/11
=>x=2/11+1/5=21/55
3: x-5/6=16/42-8/56
=>x-5/6=8/21-4/28=5/21
=>x=5/21+5/6=15/14
4: x/5=5/6-19/30
=>x/5=25/30-19/30=6/30=1/5
=>x=1
5: =>|x|=1/3+1/4=7/12
=>x=7/12 hoặc x=-7/12
6: x=-1/2+3/4
=>x=3/4-1/2=1/4
11: x-(-6/12)=9/48
=>x+1/2=3/16
=>x=3/16-1/2=-5/16
1)x= 1/4
2)x= 2/11+ 1/5
x= 21/55
3)x - 5/6 = 5/21
x = 5/21+5/6
x = 15/14
4)x/5 = 5/6 + -19/30
x:5 = 1/5
x = 1/5.5
x = 1
5) |x| - 1/4 = 6/18
|x| = 6/18 - 1/4
|x| =7/12
⇒x= 7/12 hoặc -7/12
6)x = -1/2 +3/4
x= 1/4
7) x/15 = 3/5 + -2/3
x:15 = -1/15
x = -1/15. 15
x = -1
8)11/8 + 13/6 = 85/x
85/24 = 85/x
⇒ x = 24
9) x - 7/8 = 13/12
x = 13/12 + 7/8
x = 47/24
10)x - -6/15 = 4/27
x = 4/27 + (-6/15)
x = -34/135
11) -(-6/12)+x = 9/48
x= 9/48 - 6/12
x = -5/16
12) x - 4/6 = 5/25 + -7/15
x -4/6 = -4/15
x = -4/15 + 4/6
x = 2/5
A =1/2 x 1/3 + 1/3 x 1/4 + 1/4 x 1/5 + 1/5 x 1/6 + 1/6 x 1/7 + 1/7 x 1/8 + 1/8 x 1/9
1) (3x-2)/3-2=(4x+1)/4
2) (x-3)/4+(2x-1)/3=(2-x)/6
3) 1/2 (x+1)+1/4 (x+3)=3-1/3 (x+2)
4) (x+4)/5-x+4=x/3-(x-2)/2
5) (4-5x)/6=2(-x+1)/2
6) (-(x-3))/2-2=5(x+2)/4
7)2(2x+1)/5-(6+x)/3=(5-4x)/15
8) (7-3x)/2-(5+x)/5=1
9)(x-1)/2+3(x+1)/8=(11-5x)/3
10)(3+5x)/5-3=(9x-3)/4
1) √(2x-1) <= 8-2x
2) √[(x+1)(4-x)] > x-2
3) √(x-2x^2+1) > 1-x
4) √(x+5) - √(x+4) > √(x+3)
5) √(5x-1) - √(x-1) > √(2x-4)
6) √(x+3) >= √(2x-8) + √(7-x)
7) √(x+2) - √(3-x) < √(5-2x)
8) √(x+1) > 3 - √(x+4)
9) √(5x-1) - √(4x-1)<= 3√x
10) { {√[2(x^2-16)]} / √(x-3) }+ √(x-3) > (7-x) / √(x-3)
Giúp mình 10 câu này với ạaa
Bạn nên viết đề bằng công thức toán và ghi đầy đủ yêu cầu đề để mọi người hiểu đề của bạn hơn nhé.
a, 1/2 x 1/3 + 1/3x1/4 +1/4 x 1/5 + 1/5 x 1/6 + 1/6 x 1/7 + 1/7 x 1/8 + 1/8 x 1/9 = ?
\(\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+...+\frac{1}{8}\times\frac{1}{9}=\frac{1}{2\times3}+\frac{1}{3\times4}+....+\frac{1}{8\times9}\)
\(=\frac{1}{2}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-....-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}=\frac{1}{2}-\frac{1}{9}=\frac{7}{18}\)
(1 + 1/3) x (1 + 1/8) x (1 +15) x.......x (1 + 1/9800)