x + 1/2 + x + 1/4+ x + 1/8 + x + 1/6 = 1
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
1 x 2 = ?
1 x 2 x 3 = ?
1 x 2 x 3 x 4 = ?
1 x 2 x 3 x 4 x 5 = ?
1 x 2 x 3 x 4 x 5 x 6 = ?
1 x 2 x 3 x 4 x 5 x 6 x 7 = ?
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 = ?
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 = ?
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 10 = ?
1x2= 2 1x2x3=6 1x2x3x4=24 1x2x3x4x5=120 1x2x3x4x5x6=720 1x2x3x4x5x6x7=5040
1x2x3x4x5x6x7x8=40320 1x2x3x4x5x6x7x8x9=362880 1x2x3x4x5x6x7x8x9x10=3628800
1 x 2 = 2
1 x 2 x 3 = 6
1 x 2 x 3 x 4 = 24
1 x 2 x 3 x 4 x 5 = 120
1 x 2 x 3 x 4 x 5 x 6 = 720
1 x 2 x 3 x 4 x 5 x 6 x 7 = 5040
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 = 40320
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 = 362880
1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 10 = 3628800
1 . 2 = 2
1 .2 .3 = 6
1 .2 .3 .4 = 24
1 .2 .3 .4 .5 = 120
1 .2 .3 .4 .5 .6 = 720
1 .2 .3 .4 .5 .6 .7 = 5040
1 .2 .2 .4 .5 .6 .7 .8 = 40320
1 .2 .3 .4 .5 .6 .7 .8 .9 =362880
1 .2 .3 .4 .5 .6 .7 .8 .9 .10 = 3628800
hok tốt
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 4 + 1/4 x 6 + 1/6 x 8 +1/8 x 10 + ... +1/98 x 100
2A=2/2x4+2/4x6+..+2/98x100
=> 2A=1-1/4+1/4-1/6+..+1/98-1/100
=> 2A=1-1/100
=> 2A=99/100
=> A=99/100:2
=> A=99/200
=>2/x(x+2)+2/(x+2)(x+4)+...+2/(x+6)(x+8)=8/105
=>1/x-1/x+2+1/x+2-1/x+4+...+1/x+6-1/x+8=8/105
=>\(\dfrac{1}{x}-\dfrac{1}{x+8}=\dfrac{8}{105}\)
=>x(x+8)=105
=>x^2+8x-105=0
=>(x+15)(x-7)=0
=>x=7 hoặc x=-15
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 ạ!!
1) 1/3 x 1/2 x 3/7 = 3/42 = 1/14
2) 5/4 x 1/3 +1/7 = 5/12 + 1/7 = 35/84 + 12/84 = 47/84
3) 8 x ( 8/9 - 2/3 ) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 240/240 = 1
5) ( 2/5 + 3/4 ) + 8 = 23/20 + 8 = 23//20 + 160/20 = 183/20
6) 10 x ( 1/2 - 1/5 ) = 10 x 3/10 = 10/1 x 3/10 = 30/10 = 3
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
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Tính nhanh
1/1 x 2 + 1/ 2 x 3 + 1/ 3 x 4 + 1/ 4 x 5 + 1/ 5 x 6 + 1/ 6 x 7 + 1/ 7 x 8.
\(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}+\dfrac{1}{7\times8}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}\)
\(=1-\dfrac{1}{8}=\dfrac{7}{8}\)
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 = ?
\(\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+...+\frac{1}{8}\times\frac{1}{9}=\frac{1}{2\times3}+\frac{1}{3\times4}+....+\frac{1}{8\times9}\)
\(=\frac{1}{2}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-....-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}=\frac{1}{2}-\frac{1}{9}=\frac{7}{18}\)