tim x
x-20/7 + x-46/33 + x-5/8 + x+6/19 =0
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\(\frac{x-20}{7}+\frac{x-46}{33}+\frac{x-5}{8}+\frac{x+6}{19}=0\)
\(\Leftrightarrow\)\(\left(\frac{x-20}{7}+1\right)+\left(\frac{x-46}{33}+1\right)+\left(\frac{x-5}{8}-1\right)+\left(\frac{x+6}{19}-1\right)=0\)
\(\Leftrightarrow\)\(\frac{x-13}{7}+\frac{x-13}{33}+\frac{x-13}{8}+\frac{x-13}{19}=0\)
\(\Leftrightarrow\)\(\left(x-13\right)\left(\frac{1}{7}+\frac{1}{33}+\frac{1}{8}+\frac{1}{19}\right)=0\)
\(\Leftrightarrow\)\(x-13=0\) (vi 1/7 + 1/33 + 1/8 + 1/19 \(\ne0\))
\(\Leftrightarrow\)\(x=13\)
Vậy phương trình có nghiệm là \(x=13\)
pt <=> ( x-20/7 +1 ) + ( x-46/33 + 1 ) + ( x-5/8 - 1 ) + ( x+6/19 - 1 ) = 0
<=> x-13/7 + x-13/33 + x-13/8 + x-13/19 = 0
<=> (x-13).( 1/7+1/33+1/8+1/19 ) = 0
<=> x-13 = 0 ( vì 1/7+1/33+1/8+1/19 > 0 )
<=> x=13
Vậy x=13
Tk mk nha
\(\Leftrightarrow\)\(\dfrac{x}{7}-\dfrac{20}{7}+\dfrac{x}{33}-\dfrac{46}{33}+\dfrac{x}{8}-\dfrac{5}{8}+\dfrac{x}{19}+\dfrac{6}{19}=0\)
\(\dfrac{5016x}{35112}+\dfrac{1064x}{35112}+\dfrac{4389x}{35112}+\dfrac{1848x}{35112}=\dfrac{100320}{35112}+\dfrac{48994}{35112}-\dfrac{21945}{35112}+\dfrac{11088}{35112}\)
\(\dfrac{12317x}{35112}=\dfrac{160121}{35112}\)
\(12317x=160121\)
\(x=13\)
Làm cách này nhưng tớ thấy nó vẫn không tiến triển gì, thôi, qua cái này:
\(\dfrac{x-20}{7}+\dfrac{x-46}{33}+\dfrac{x-5}{8}+\dfrac{x+6}{19}=0\)
\(\dfrac{5016\left(x-20\right)+1064\left(x-46\right)+4389\left(x-5\right)+1848\left(x+6\right)}{35112}=0\)
\(5016x+1064x+4389x+1848x=100320+48944+21945-11088\)
\(12317x=160121\)
\(x=13\)
\(\Leftrightarrow\frac{x-20}{7}+1+\frac{x-46}{33}+1+\frac{x-5}{8}-1+\frac{x+6}{19}-1=0\)
\(\Leftrightarrow\frac{x-13}{7}+\frac{x-13}{33}+\frac{x-13}{8}+\frac{x-13}{19}=0\)
\(\Leftrightarrow\left(x-13\right)\left(\frac{1}{7}+\frac{1}{33}+\frac{1}{8}+\frac{1}{19}\right)=0\)
\(\Leftrightarrow x-13=0\)
\(\Leftrightarrow x=13\)
Câu B đây;vừa bị lag
B, \(\frac{x+1}{35}\)+\(\frac{x+3}{33}\)=\(\frac{x+5}{31}\)+\(\frac{x+7}{29}\)
⇔ \(\frac{x+1}{35}\)+1+\(\frac{x+3}{33}\)+1=\(\frac{x+5}{31}\)+1+\(\frac{x+7}{29}\)+1
⇔ \(\frac{x+36}{35}\)+\(\frac{x+36}{33}\)-\(\frac{x+36}{31}\)-\(\frac{x+36}{29}\)=0
⇔ (x+36)(\(\frac{1}{35}\)+\(\frac{1}{33}\)-\(\frac{1}{31}\)-\(\frac{1}{29}\))=0
Mà \(\frac{1}{35}\)+\(\frac{1}{33}\)-\(\frac{1}{31}\)-\(\frac{1}{29}\)<0
⇔ x+36=0
⇔ x=-36
Vậy tập nghiệm của phương trình đã cho là:S={-36}
câu C tương tự nhé
1) x - 2 = -6
x = -6 + 2
x = -4
2) -5 . x - ( -3 ) =13
-5 . x = 13 + ( -3 )
-5 . x = 10
x = 10 : ( -5 )
x = -2
a: =>33+x=71-36=35
=>x=2
b: =>(2x+6)=200-64=136
=>2x=130
=>x=65
c: =>x-19=76
=>x=95
e: =>x+9=39
=>x=30
f: =>x-8=20
=>x=28
g: =>2x=5*9+49=45+49=94
=>x=47
1) ( x - 2 ) . ( x + 15 ) = 0
\(\Rightarrow\) x - 2 = 0 hoặc x + 15 = 0
* Nếu x - 2 = 0
x = 0 + 2
x = 2
* Nếu x + 15 = 0
x = 0 - 15
x = -15
Vậy x \(\in\) { 2 ; -15 }
2) ( 7 - x ) . ( x + 19 ) = 0
\(\Rightarrow\) 7 - x = 0 hoặc x + 19 = 0
* Nếu 7 - x = 0
x = 7 - 0
x = 7
* Nếu x + 19 = 0
x = 0 - 19
x = -19
Vậy x \(\in\) {7 ; -19}
13) –12(x -5) + 7(3 -x) = 5
→ -12x + 60 + 21 - 7x = 5
→ -12x - 7x = 5 - 60 - 21
→ -19x = -76
→ x = -76 : ( - 19 )
→ x = 4
14) (x –2).(x + 4) = 0
→ ( x - 2 ) . ( x + 4 ) = 0 ↔ x - 2 = 0 hoặc x + 4 = 0 ( chọn 1 cách thôi nhé )
→ x = 0 + 2 = 2 hoặc x = 0 - 4 = -4
15) (x –2).( x + 15) = 0 ( làm giống câu trên )
16) (7–x).( x + 19) = 0 ( làm giống câu trên )
17) -5<x<1
→ x ϵ -4 ; -3 ; -2 ; -1 ; 0
18) /x/<3
→ x ϵ -2 ; -1 ; 0 ; 1 ; 2
19) (x –3)(x –5) < 0
→ x - 3 . x - 5 < 0
→ 2x - 15 < 0
→ 2x < 0 + 15 = 15
→ x < 15 : 2 = 7,5
→ x ϵ ....... ( bạn tự ghi nhé )
20) 2x2–3 = 29( đề bài sai )
21) –6x –(–7) = 25
→ -6x + 7 = 25
→ -6x = 25 - 7 = 18
→ x = 18 : ( - 6 ) = -3
22) 46 –( x –11 ) = –48
→ 46 - x + 11 = -48
→ -x = -48 - 11 - 46 = -105
→ x = 105
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)