3/4+1/4:x=-3
a,1/3 .(x-2/5)=3/4 b, 7/3:(x-2/3)=4/5 c,1/3.(x-2/5)=4/5 d, 2/3.(x-1/2)-1/4.(x-2/5)=7/3 e,3/7 .(x-2/3)+1/2=5/4.(x-2) f,1/2.(x-3)+1/3.(x-4)+1/4.(x-5)=1/5 g,[2/3.(x-1/2)-4/5]:(x-1/3)=21/5 h, {x-[1/2.(x-3)+11/5]}:(x-1/2)=3/5 i,x.(x-2/5)-(x+2).x+11/4=4/3
a: =>x-2/5=3/4:1/3=3/4*3=9/4
=>x=9/4+2/5=45/20+8/20=53/20
b: =>x-2/3=7/3:4/5=7/3*5/4=35/12
=>x=35/12+2/3=43/12
c: 1/3(x-2/5)=4/5
=>x-2/5=4/5*3=12/5
=>x=12/5+2/5=14/5
d: =>2/3x-1/3-1/4x+1/10=7/3
=>5/12x-7/30=7/3
=>5/12x=7/3+7/30=77/30
=>x=77/30:5/12=154/25
e: \(\Leftrightarrow x\cdot\dfrac{3}{7}-\dfrac{2}{7}+\dfrac{1}{2}-\dfrac{5}{4}x+\dfrac{5}{2}=0\)
=>\(x\cdot\dfrac{-23}{28}=\dfrac{2}{7}-3=\dfrac{-19}{7}\)
=>x=19/7:23/28=76/23
f: =>1/2x-3/2+1/3x-4/3+1/4x-5/4=1/5
=>13/12x=1/5+3/2+4/3+5/4=257/60
=>x=257/65
i: =>x^2-2/5x-x^2-2x+11/4=4/3
=>-12/5x=4/3-11/4=-17/12
=>x=17/12:12/5=85/144
1.tính thuận tiện
a. 2/3 x 4/5 + 1/3 x 4/5
b. 2/3 x 4/5 - 1/3 x 4/5
c. 1/2 : 3/4 + 1/6 : 3/4
d. 1/2 : 3/4 - 1/6 : 3/4
a)\(\dfrac{2}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}+\dfrac{1}{3}\right).\dfrac{4}{5}=1.\dfrac{4}{5}=\dfrac{4}{5}\)
b)\(\dfrac{2}{3}.\dfrac{4}{5}-\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}-\dfrac{1}{3}\right).\dfrac{4}{5}=\dfrac{1}{3}.\dfrac{4}{5}=\dfrac{4}{15}\)
a) \(\dfrac{2}{3}\times\dfrac{4}{5}+\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{4}{5}\times1=\dfrac{4}{5}\)
b) \(\dfrac{2}{3}\times\dfrac{4}{5}-\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}-\dfrac{1}{3}\right)=\dfrac{4}{5}\times\dfrac{1}{3}=\dfrac{4}{15}\)
c) \(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}+\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\times\left(\dfrac{1}{2}+\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{2}{3}=\dfrac{8}{9}\)
d) \(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}-\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{1}{3}=\dfrac{4}{9}\)
c)\(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}.\dfrac{4}{3}+\dfrac{1}{6}.\dfrac{4}{3}=\left(\dfrac{1}{2}+\dfrac{1}{6}\right).\dfrac{4}{3}=\dfrac{2}{3}.\dfrac{4}{3}=\dfrac{8}{9}\)
d)\(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}.\dfrac{4}{3}-\dfrac{1}{6}.\dfrac{4}{3}=\left(\dfrac{1}{2}-\dfrac{1}{6}\right).\dfrac{4}{3}=\dfrac{1}{3}.\dfrac{4}{3}=\dfrac{4}{9}\)
bài 3:
a) x - 3/4 = 6 x 3/8 b) 7/8 : x = 3 - 1/2 c) x + 1/2 x 1/3 = 3/4
d) 3/2 x 4/5 - x = 2/3 e) X x 3 1/3 = 3 1/3 : 4 1/4 f) 5 2/3 : x = 3 2/3 - 2 1/2
a) \(x-\dfrac{3}{4}=6\times\dfrac{3}{8}\)
\(x-\dfrac{3}{4}=\dfrac{9}{4}\)
=> \(x=\dfrac{9}{4}+\dfrac{3}{4}=3\)
b) \(\dfrac{7}{8}:x=3-\dfrac{1}{2}\)
\(\dfrac{7}{8}:x=\dfrac{5}{2}\)
=> \(x=\dfrac{7}{8}:\dfrac{5}{2}=\dfrac{7}{20}\)
c) \(x+\dfrac{1}{2}\times\dfrac{1}{3}=\dfrac{3}{4}\)
\(x+\dfrac{1}{6}=\dfrac{3}{4}\)
=> \(x=\dfrac{3}{4}-\dfrac{1}{6}=\dfrac{7}{12}\)
d) \(\dfrac{3}{2}\times\dfrac{4}{5}-x=\dfrac{2}{3}\)
\(\dfrac{6}{5}-x=\dfrac{2}{3}\)
=> \(x=\dfrac{6}{5}-\dfrac{2}{3}=\dfrac{8}{15}\)
e) \(x\times3\dfrac{1}{3}=3\dfrac{1}{3}:4\dfrac{1}{4}\)(?)
\(x\times\dfrac{10}{3}=\dfrac{40}{51}\)
=> \(x=\dfrac{40}{51}:\dfrac{10}{3}=\dfrac{4}{17}\)
f) \(5\dfrac{2}{3}:x=3\dfrac{2}{3}-2\)
\(\dfrac{17}{3}:x=\dfrac{5}{3}\)
=> \(x=\dfrac{17}{3}:\dfrac{5}{3}=\dfrac{17}{5}\)
a: =>x-3/4=18/8=9/4
=>x=9/4+3/4=12/4=3
b: =>7/8:x=5/2
=>x=7/8:5/2=7/8*2/5=14/40=7/20
c: x+1/2*1/3=3/4
=>x+1/6=3/4
=>x=3/4-1/6=9/12-2/12=7/12
d: =>12/10-x=2/3
=>6/5-x=2/3
=>x=6/5-2/3=18/15-10/15=8/15
e: =>x*10/3=10/3:17/4=10/3*4/17
=>x=4/17
f: =>17/3:x=13/3-5/2=26/6-15/6=11/6
=>x=17/3:11/6=17/3*6/11=34/11
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
a,7/4+-3/5
b,2021-(1/3)^2 x 3^2
c,7,5 x(-3/5)
d,(-1/4)^2 x 4/11+7/11 x(-1/4)^2
e, A= 1/4 +1/4^2+1/4^3+...+1/4^2020<1/3
a: \(\dfrac{7}{4}+\dfrac{-3}{5}=\dfrac{35-12}{20}=\dfrac{23}{20}\)
d: \(\left(-\dfrac{1}{4}\right)^2\cdot\dfrac{4}{11}+\dfrac{7}{11}\cdot\left(-\dfrac{1}{4}\right)^2=\dfrac{1}{16}\)
\(\dfrac{7}{4}+\dfrac{-3}{5}=\dfrac{35}{20}+\dfrac{-12}{20}=\dfrac{23}{20}\)
tìm x , biết
1 . 3 3/4 : x = 1 1/2
2 . 1 1/4 x + 2 1/2 = 1 1/4
3 . ( 3 1/3 - 1 1/2 x ) : 5/6 = 1 1/2
4 . ( 3/7 x - 1 ) : 4 = -1/28
5 . 2 2/3 x - x = 3 3/4
6 . | x - 3/4 | = 1
7 . | 2/3 x + 1/3 | = 5/6
a) 3 3/4 . x = 1 1/2
<=> 15/4 . x = 3/2
<=> x = 3/4 . 4/15
<=> x = 1/5
Vậy x = 1/5
b) 1 1/4 x + 1 1/2 = 1 1/4
<=> 5/4 . x + 3/2 = 5/4
<=> 5/4 . x = 5/4 - 3/2
<=> 5/4 . x = -1/4
<=> x = -1/4 . 4/5
<=> x = -1/5
Vậy x = -1/5
c) ( 3 1/3 - 1 1/2 x ) : 5/6 = 1 1/2
<=> ( 10/3 - 3/2 x ) : 5/6 = 3/2
<=> 10/3 - 3/2 x = 3/2 . 5/6
<=> 10/3 - 3/2 x = 5/4
<=> 3/2 . x = 10/3 - 5/4
<=> 3/2 . x = 25/12
<=> x = 25/12 . 2/3
<=> x = 25/18
Vậy x = 25/18
d) ( 3/7 x - 1 ) : 4 = -1/28
<=> 3/7 . x - 1 = -1/28 . 1/4
<=> 3/7 . x - 1 = -1/112
<=> 3/7 . x = -1/112 + 1
<=> 3/7 . x = 111/112
<=> x = 111/112 . 7/3
<=> x = 37/16
Vậy x = 37/16
e) | x - 3/4 | = 1
<=> x - 3/4 = 1
hoặc x - 3/4 = -1
<=> x = 1 + 3/4
hoặc x = -1 + 3/4
<=> x = 7/4
hoặc x = -1/4
Vậy x = 7/4 ; x = -1/4
f) | 2/3 . x + 1/3 | = 5/6
<=> 2/3 . x + 1/3 = 5/6
hoặc 2/3 . x + 1/3 = -5/6
<=> 2/3 . x = 5/6 - 1/3
hoặc 2/3 . x = -5/6 - 1/3
<=> 2/3 . x = 1/2
hoặc 2/3 . x = -7/6
<=> x = 1/2 . 3/2
hoặc x = -7/6 . 3/2
<=> x = 3/4
hoặc x = -7/4
Vậy x = 3/4 ; x = -7/4
Giải phương trình về dạng ax + b = 0
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
Giải phương trình về dạng ax + b = 0
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
Quy đồng mẫu số của 1 phần 3; 4 phần 5 và 3 phần 4
1 | = | 1 x 5 x ? | = = | 20 |
3 | 3 x ? x 4 | ? |
4 | = | 4 x 3 x 4 | = = | 48 |
5 | 5 x ? x 4 | ? |
3 | = | 3 x 5 x ? | = = | ? |
4 | 4 x 5 x ?? | ? |
1) (3x-2)/3-2=(4x+1)/42) (x-3)/4+(2x-1)/3=(2-x)/63) 1/2 (x+1)+1/4 (x+3)=3-1/3 (x+2)4) (x+4)/5-x+4=x/3-(x-2)/25) (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)/158) (7-3x)/2-(5+x)/5=1 9)(x-1)/2+3(x+1)/8=(11-5x)/310)(3+5x)/5-3=(9x-3)/4