5.x - 9 = 5 + 3.x

5x - 3x = 5 + 9

2x = 14

x = 14 : 2

x = 7

--------------------

(5x + 1)² = 36/49

5x + 1 = 6/7 hoặc 5x + 1 = -6/7

*) 5x + 1 = 6/7

5x = 6/7 - 1

5x = -1/7

x = -1/7 : 5

x = -1/35

*) 5x + 1 = -6/7

5x = -6/7 - 1

5x = -13/7

x = -13/7 : 5

x = -13/35

Vậy x = -13/35; x = -1/35

--------------------

2ˣ⁻¹ = 16

2ˣ⁻¹ = 2⁴

x - 1 = 4

x = 4 + 1

x = 5

c, (2\(\times\) \(x\) - 3) \(\times\) 5 = 4

    2 \(\times\) \(x\) - 3       = \(\dfrac{4}{5}\)

     2 \(\times\) \(x\)            = 0,8 + 3

      2\(x\)                = 3,8

        \(x\)                 = \(3,8\) : 2

        \(x\)                 = 1,9 

d, 1 + 3 + 5 +....+\(x\)   = 36

    (\(x\) + 1)\(\times\) \(x\): 2      = 36

     (\(x+1\)) \(\times\)\(x\)         = 72 

     (\(x+1\))\(\times\)\(x\)           = 8 x 9

      \(x\)                         = 8

a) (X - 5) x 4 = 36

⇒         X - 5 = 36 : 4

⇒         X - 5 = 9

⇒              X = 9 + 5

⇒              X = 14

     Vậy X = 14 

b) (48 - X) x 2 = 14

⇒         48 - X = 14 : 2

⇒         48 - X = 7

⇒                X = 48 - 7

⇒                X = 41

    Vậy X = 41

\(B=\frac{36}{1.3.5}+\frac{36}{3.5.7}+\frac{36}{5.7.9}+...+\frac{36}{25.27.29}\)

   \(=9.\left(\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+...+\frac{4}{25.27.29}\right)\)

    \(=9.\left(\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+\frac{1}{5.7}-\frac{1}{7.9}+...+\frac{1}{25.27}-\frac{1}{27.29}\right)\)

    \(=9.\left(\frac{1}{3}-\frac{1}{675}\right)\)

    \(=9.\frac{224}{675}\)

    \(=\frac{224}{75}\)

THIẾU

\(=\frac{224}{75}< \frac{225}{75}=3\)

Vậy \(B< 3\)

mấy bọn nguuuuuuuuuuuuuuuuuu

x-36/18+2.x+5=19+2.(x-1)

x-2+2x+5=19+2x-1.2

3x-2+5=2x-2+19

3x+3=2x+17

3x=2x+14

x=14

\(x-36:18+2.x+5=19+2\left(x-1\right)\)

\(\Leftrightarrow x+2x+5-\frac{36}{18}=19+2\left(x-1\right)\)

\(\Leftrightarrow3x+5-\frac{38}{16}=19+2\left(x-1\right)\)

\(\Leftrightarrow3x+5-2=19+2\left(x-1\right)\)

\(\Leftrightarrow3x+3=19+2\left(x-1\right)\)

\(\Leftrightarrow3x+3=2x+17\)

\(\Leftrightarrow3x=2x+17-3\)

\(\Leftrightarrow3x=2x+14\)

\(\Leftrightarrow3x=2x+14-2x\)

\(\Leftrightarrow x=14\)

=> x = 14

\(20x^3-10x^2+5x-20x^3+10x^2-4x=0\)

\(\left(20x^3-20x^3\right)+\left(-10x^2+10x^2\right)+\left(5x-4x\right)=0\)

\(x=0\)

 5x∙4x²-5x∙2x+5x∙1+-2x∙10x²--2x∙5x+-2x∙2=-36

  20x³  - 10x²+  5x +   -20x³  -  10x²+  - 4x   =-36

 (20x³                          -20x³)+(-10x²-10x²)+(5x-4x)=-36

                                                                          x      =-36

5x(4x2−2x+1)−2x(10x2−5x+2)=−36 

5�.4�2+5�.(−2�)+5�.1+(−2�).10�2+(−2�).(−5�)+(−2�).2=−365x.4x2+5x.(−2x)+5x.1+(−2x).10x2+(−2x).(−5x)+(−2x).2=−36 

20�3+(−10�2)+5�+(−20�3)+10�2+(−4�)=−3620x3+(−10x2)+5x+(−20x3)+10x2+(−4x)=−36

(20�3−20�3)+(−10�2+10�2)+(5�−4�)=−36(20x3−20x3)+(−10x2+10x2)+(5x−4x)=−36

$x=-36$

Vậy $x=-36$.

\(a,96-3\left(x+8\right)=42\\ \Rightarrow3\left(x+8\right)=54\\ \Rightarrow x+8=18\\ \Rightarrow x=10.\\ b,15.5\left(x-25\right)-225=0\\ \Rightarrow75\left(x-25\right)-225=0\\ \Rightarrow75\left(x-25\right)=225\\ \Rightarrow x-25=3\\ \Rightarrow x=28.\\ c,250:x+15=25\\ \Rightarrow250:x=10\\ \Rightarrow x=25\\ d,36:\left(x-5\right)=2^2\\ \Rightarrow36:\left(x-5\right)=4\\ \Rightarrow x-5=9\\ \Rightarrow x=14.\\ e,\left[3.\left(70-x\right)+5\right]:2=46\\ \Rightarrow3.\left(70-x\right)+5=92\\ \Rightarrow3\left(70-x\right)=87\\ \Rightarrow70-x=29\\ \Rightarrow x=41.\)

a: =>x(5-2)=120

=>3x=120

=>x=40

b: =>x(13-10)=240

=>3x=240

=>x=80

c; =>10x=250

=>x=25

d: =>3x=36

=>x=12

a: Ta có: \(\left(x+2\right)^2+\left(2x-1\right)^2-\left(x-3\right)^2=36\)

\(\Leftrightarrow x^2+4x+4+4x^2-4x+1-x^2+6x-9=36\)

\(\Leftrightarrow4x^2+6x-4-36=0\)

\(\Leftrightarrow4x^2+6x-40=0\)

\(\text{Δ}=6^2-4\cdot4\cdot\left(-40\right)=676\)

Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:

\(\left\{{}\begin{matrix}x_1=\dfrac{-6-26}{8}=-4\\x_2=\dfrac{-6+26}{8}=\dfrac{5}{2}\end{matrix}\right.\)