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1 tháng 2 2019

Viết sai đề rùi nha bn

Đề đây, mk giải lun

(x-1)/13-(2x-13)/15=(3x-15)/27-(4x-27)/29

<=>15(x-1)/195-13(2x-13)/195=3(x-5)/27-4x-27/29

<=>15x-15-26x+169/195=29(x-5)/261-9(4x-27)/261

<=>-11+154/195=29x-145-36x+243/261

<=>-11x+154/195=-7x+98/261

<=>(11x+154)261=195(7x+98)

<=>2871x=-21084

<=>x=-14

Vậy x= -14

30 tháng 5 2018

\(\dfrac{x-1}{13}-\dfrac{2x-13}{15}=\dfrac{3x-15}{27}-\dfrac{2x-27}{29}\)

\(\Leftrightarrow\dfrac{x-1}{13}-1-\dfrac{2x-13}{15}-1=\dfrac{3x-15}{27}-1-\dfrac{2x-27}{29}-1\)

\(\Leftrightarrow\dfrac{x-1-13}{13}-\dfrac{2x-13-15}{15}=\dfrac{3x-15-27}{27}-\dfrac{4x-27-29}{29}\)

\(\Leftrightarrow\dfrac{x-14}{13}-\dfrac{2x-24}{15}=\dfrac{3x-42}{27}-\dfrac{4x-56}{29}\)

\(\Leftrightarrow\dfrac{x-14}{13}-\dfrac{2\left(x-14\right)}{15}-\dfrac{3\left(x-14\right)}{27}-\dfrac{4\left(x-14\right)}{29}=0\)

\(\Leftrightarrow\left(x-14\right)\left(\dfrac{1}{13}-\dfrac{2}{15}-\dfrac{3}{27}-\dfrac{4}{29}\right)=0\)

\(\Leftrightarrow x-14=0\) ( Vì: \(\dfrac{1}{13}-\dfrac{2}{15}-\dfrac{3}{27}-\dfrac{4}{29}\ne0\))

\(\Leftrightarrow x=14\)

4 tháng 10 2018

x=-36

x=11

x=100

x=14

4 tháng 10 2018

x=-36

x=11

x=100

x=14

11 tháng 3 2021

1) PT \(\Leftrightarrow\left(\dfrac{x+1}{35}+1\right)+\left(\dfrac{x+3}{33}+1\right)=\left(\dfrac{x+5}{31}+1\right)+\left(\dfrac{x+7}{29}+1\right)\)

\(\Leftrightarrow\dfrac{x+36}{35}+\dfrac{x+36}{33}=\dfrac{x+36}{31}+\dfrac{x+36}{29}\)

\(\Leftrightarrow\left(x+36\right)\left(\dfrac{1}{29}+\dfrac{1}{31}-\dfrac{1}{33}-\dfrac{1}{35}\right)=0\)

\(\Leftrightarrow x+36=0\) (Do \(\dfrac{1}{29}+\dfrac{1}{31}-\dfrac{1}{33}-\dfrac{1}{35}>0\))

\(\Leftrightarrow x=-36\).

Vậy nghiệm của pt là x = -36.

17 tháng 7

2) x(x+1)(x+2)(x+3)= 24

⇔ x.(x+3)  .   (x+2).(x+1)  = 24

⇔(\(x^2\) + 3x) . (\(x^2\) + 3x + 2) = 24

Đặt \(x^2\)+ 3x = b

⇒ b . (b+2)= 24

Hay: \(b^2\) +2b = 24

\(b^2\) + 2b + 1 = 25

\(\left(b+1\right)^2\)= 25

+ Xét b+1 = 5 ⇒ b=4 ⇒  \(x^2\)+ 3x = 4 ⇒ \(x^2\)+4x-x-4=0 ⇒x(x+4)-(x+4)=0

⇒(x-1)(x+4)=0⇒x=1 và x=-4

+ Xét b+1 = -5 ⇒ b=-6 ⇒ \(x^2\)+3x=-6 ⇒\(x^2\) + 3x + 6=0

\(x^2\) + 2.x.\(\dfrac{3}{2}\) + (\(\dfrac{3}{2}\))2 = - \(\dfrac{15}{4}\)  Hay ( \(x^2\) +\(\dfrac{3}{2}\) )2= -\(\dfrac{15}{4}\) (vô lí)

⇒x= 1 và x= 4

4 tháng 4 2019

a)\(\Leftrightarrow\left(x-100\right)\left(\frac{1}{15}+\frac{1}{13}+\frac{1}{11}+\frac{1}{9}\right)=0\)(Trừ từng số hạng cho 1;2;3;4 rồi nhóm)

Vậy x=100.

b)\(\Leftrightarrow\left(x-14\right)\left(\frac{1}{13}-\frac{1}{15}-\frac{1}{27}+\frac{1}{29}\right)=0\)(Trừ từng số cho 1)

Vậy x=14.

19 tháng 4 2020

\(\frac{x-1}{13}-\frac{2x-13}{15}=\frac{3x-15}{27}-\frac{4x-27}{29}\)

\(\Leftrightarrow\left(\frac{x-1}{13}-1\right)-\left(\frac{2x-13}{15}-1\right)=\left(\frac{3x-15}{27}-1\right)-\left(\frac{4x-27}{29}-1\right)\)

\(\Leftrightarrow\frac{x-14}{13}-\frac{2\left(x-14\right)}{15}=\frac{3\left(x-14\right)}{27}-\frac{4\left(x-14\right)}{29}\)

\(\Leftrightarrow\left(x-14\right)\left(\frac{1}{13}-\frac{2}{15}-\frac{3}{27}+\frac{4}{29}\right)=0\)

<=> x-14=0

<=> x=14

19 tháng 4 2020

\(\frac{x-1}{13}-\frac{2x-13}{15}=\frac{3x-15}{27}-\frac{4x-27}{29}\)

\(\Leftrightarrow\frac{x-1}{13}-1-\frac{2x-13}{15}+1=\frac{3x-15}{27}-1-\frac{4x-27}{29}+1\)

\(\Leftrightarrow\left(\frac{x-1}{13}-1\right)-\left(\frac{2x-13}{15}-1\right)=\left(\frac{3x-15}{27}-1\right)-\left(\frac{4x-27}{29}-1\right)\)

\(\Leftrightarrow\frac{x-14}{13}-\frac{2x-28}{15}=\frac{3x-42}{27}-\frac{4x-56}{29}\)

\(\Leftrightarrow\frac{x-14}{13}-\frac{2\left(x-14\right)}{15}=\frac{3\left(x-14\right)}{27}-\frac{4\left(x-14\right)}{29}\)

\(\Leftrightarrow\frac{x-14}{13}-\frac{2\left(x-14\right)}{15}-\frac{3\left(x-14\right)}{27}+\frac{4\left(x-14\right)}{29}=0\)

\(\Leftrightarrow\left(x-14\right)\left(\frac{1}{13}-\frac{2}{15}-\frac{3}{27}+\frac{4}{29}\right)=0\)

Vì \(\frac{1}{13}-\frac{2}{15}-\frac{3}{27}+\frac{4}{29}\ne0\)

\(\Rightarrow x-14=0\)\(\Leftrightarrow x=14\)

Vậy tập nghiệm của phương trình là \(S=\left\{14\right\}\)

4 tháng 2 2017

Phương trình 1:
\(\frac{x-85}{15}+\frac{x-74}{13}+\frac{x-67}{11}+\frac{x-64}{9}=10\)
\(\Rightarrow\frac{x-85}{15}+\frac{x-74}{13}+\frac{x-67}{11}+\frac{x-64}{9}-10=0\)
\(\Rightarrow\left(\frac{x-85}{15}-1\right)+\left(\frac{x-74}{13}-2\right)+\left(\frac{x-67}{11}-3\right)+\left(\frac{x-64}{9}-4\right)=0\)
\(\Rightarrow\frac{x-85-15}{15}+\frac{x-74-26}{13}+\frac{x-67-33}{11}+\frac{x-64-36}{9}=0\)
\(\Rightarrow\frac{x-100}{15}+\frac{x-100}{13}+\frac{x-100}{11}+\frac{x-100}{9}=0\)
\(\Rightarrow\left(x-100\right)\left(\frac{1}{15}+\frac{1}{13}+\frac{1}{11}+\frac{1}{9}\right)=0\)
Do \(\frac{1}{15}+\frac{1}{13}+\frac{1}{11}+\frac{1}{9}\ne0\)
\(\Rightarrow x-100=0\)
\(\Rightarrow x=100\)
Vậy x = 100.

4 tháng 2 2017

Phương trình 3:
\(\frac{1909-x}{91}+\frac{1907-x}{93}+\frac{1905-x}{95}+\frac{1903-x}{97}+4=0\)
\(\Rightarrow\left(\frac{1909-x}{91}+1\right)+\left(\frac{1907-x}{93}+1\right)+\left(\frac{1905-x}{95}+1\right)+\left(\frac{1903-x}{97}+1\right)=0\)
\(\Rightarrow\frac{1909-x+91}{91}+\frac{1907-x+93}{93}+\frac{1905-x+95}{95}+\frac{1903-x+97}{97}=0\)
\(\Rightarrow\frac{2000-x}{91}+\frac{2000-x}{93}+\frac{2000-x}{95}+\frac{2000-x}{97}=0\)
\(\Rightarrow\left(2000-x\right)\left(\frac{1}{91}+\frac{1}{93}+\frac{1}{95}+\frac{1}{97}\right)=0\)
Do \(\frac{1}{91}+\frac{1}{93}+\frac{1}{95}+\frac{1}{97}\ne0\)
\(\Rightarrow2000-x=0\)
\(\Rightarrow x=2000\)
Vậy x = 2000.