2 mũ 6 x bằng 6

2 mũ 5 trừ 2 bằng 30 x = 5

x bằng 12

x bằng 4

x= 4

\(2^x=64\Leftrightarrow2^x=2^6\Leftrightarrow x=6\)

\(2^x-2=30\Leftrightarrow2^x=32\Leftrightarrow2^x=2^5\Leftrightarrow x=5\)

\(18:\left(x-6\right)=3\Leftrightarrow x-6=6\Leftrightarrow x=6+6=12\)

\(3^x-1=80\Leftrightarrow3^x=81\Leftrightarrow3^x=3^4\Leftrightarrow x=4\)

\(240:\left(2x-4\right)=60\Leftrightarrow2x-4=4\Leftrightarrow2x=8\Leftrightarrow x=4\)

\(143-5^{3-x}=3^3\times2^0\Leftrightarrow143-5^{3-x}=27\times1\)

\(\Leftrightarrow143-5^{3-x}=27\Leftrightarrow5^{3-x}=143-27=116\)

mà \(5^{3-x}\ne116\Leftrightarrow x\in\varnothing\)

Vậy: \(x\in\varnothing\)

Nhớ k cho mình nhé! Thank you!!!

\(2^x=64\)

\(2^x=2^6\)

\(\Rightarrow x=6\)

\(2^x-2=30\)

\(2^x=30+2\Rightarrow2^x=32\)

\(\Rightarrow2^x=2^5\)

\(\Rightarrow x=5\)

3^x-1=80

3^x=80+1

3^x=81

3^x=3⁴

=> x=4

240:[2x-4]=60

       [2x-4]=240:60

      [2x-4]=4

      2x=4+4

      2x=8

      x=8:2

      x=4

Ys cuối bạn tự làm nha dễ mà.

1) 4x-(2x-5)=21

4x-2x+5=21

2x+5=21

2x=21 -5

2x=16

x=16/2

x=8

2)14x+5=8x+10

14x-8x=10-5

6x=5

x=5/6

3) 15+5x=3x+30

5x-3x=30-15

2x=15

x=15/2

Vậy x=15/2

4.

\((2x+7)(x+3)^2(2x+5)=18\)

\(\Leftrightarrow [(2x+7)(2x+5)](x+3)^2=18\)

\(\Leftrightarrow (4x^2+24x+35)(x^2+6x+9)=18\)

\(\Leftrightarrow [4(x^2+6x+9)-1](x^2+6x+9)=18\)

\(\Leftrightarrow (4a-1)a=18\) (đặt \(x^2+6x+9=a\) )

\(\Leftrightarrow 4a^2-a-18=0\)

\(\Leftrightarrow (4a-9)(a+2)=0\Rightarrow \left[\begin{matrix} a=\frac{9}{4}\\ a=-2\end{matrix}\right.\)

Nếu \(a=x^2+6x+9=\frac{9}{4}\Leftrightarrow (x+3)^2=\frac{9}{4}\)

\(\Rightarrow \left[\begin{matrix} x+3=\frac{3}{2}\\ x+3=\frac{-3}{2}\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=\frac{-3}{2}\\ x=\frac{-9}{2}\end{matrix}\right.\)

Nếu \(a=x^2+6x+9=-2\Leftrightarrow (x+3)^2=-2< 0\) (vô lý)

Vậy ............

5.

PT \(\Leftrightarrow (x-1)(x-2)(2x-3)(2x-5)=30\)

\(\Leftrightarrow [(x-1)(2x-5)][(x-2)(2x-3)]=30\)

\(\Leftrightarrow (2x^2-7x+5)(2x^2-7x+6)=30\)

Đặt \(2x^2-7x+5=a\) thì:

PT \(\Leftrightarrow a(a+1)=30\)

\(\Leftrightarrow a^2+a-30=0\)

\(\Leftrightarrow (a-5)(a+6)=0\Rightarrow \left[\begin{matrix} a-5=0\\ a+6=0\end{matrix}\right.\)

Nếu \(a-5=0\Leftrightarrow 2x^2-7x=0\Leftrightarrow x(2x-7)=0\)

\(\Rightarrow \left[\begin{matrix} x=0\\ x=\frac{7}{2}\end{matrix}\right.\)

Nếu \(a+6=0\Leftrightarrow 2x^2-7x+11=0\)

\(\Leftrightarrow 2(x-\frac{7}{4})^2+\frac{39}{8}=0\Leftrightarrow 2(x-\frac{7}{4})^2=-\frac{39}{8}<0\) (vô lý)

Vậy...........

6.

PT\(\Leftrightarrow (x+1)(x+2)(x+3)(x+4)=24\)

\(\Leftrightarrow [(x+1)(x+4)][(x+2)(x+3)]=24\)

\(\Leftrightarrow (x^2+5x+4)(x^2+5x+6)=24\)

\(\Leftrightarrow (a+4)(a+6)=24\) (đặt \(x^2+5x=a\) )

\(\Leftrightarrow a^2+10a=0\Leftrightarrow a(a+10)=0\Rightarrow \left[\begin{matrix} a=0\\ a+10=0\end{matrix}\right.\)

Nếu \(a=0\Leftrightarrow x^2+5x=0\Leftrightarrow x(x+5)=0\Leftrightarrow \left[\begin{matrix} x=0\\ x=-5\end{matrix}\right.\)

Nếu \(a+10=0\Leftrightarrow x^2+5x+10=0\Leftrightarrow (x+\frac{5}{2})^2+\frac{15}{4}=0\)

\(\Leftrightarrow (x+\frac{5}{2})^2=-\frac{15}{4}\) (vô lý)

Vậy...........

Noob ơi, bạn phải đưa vào máy tính ý solve cái là ra x luôn, chỉ tội là đợi hơi lâu

a, 4.(18 - 5x) - 12(3x - 7) = 15(2x - 16) - 6(x + 14) 

=> 72 - 20x - 36x + 84 = 30x - 240 - 6x - 84

=> (72 + 84) + (-20x - 36x) = (30x - 6x) + (-240 - 84) 

=> 156 -  56x = 24x - 324 

=>  24x + 56x = 324 + 156 

=> 80x = 480 

=> x = 480 : 80 =  6 

Vậy x = 6 

b, 5(3x + 5) - 4(2x - 3) = 5x + 3(2x + 12) + 1 

=> 15x + 25 - 8x + 12 = 5x + 6x + 36 + 1 

=> (15x - 8x) + (25 + 12) = 11x + 37 

=> 7x + 37 = 11x + 37 

=> 11x - 7x = 0 

=>  x = 0 

\(\frac{3}{x+1}+\frac{2}{x+2}=\frac{5x+4}{x^2+3x+2}.\)ĐKXĐ: \(x\ne-1;-2\)

\(\Leftrightarrow\frac{3\left(x+2\right)}{\left(x+1\right)\left(x+2\right)}+\frac{2\left(x+1\right)}{\left(x+1\right)\left(x+2\right)}=\frac{5x+4}{\left(x+1\right)\left(x+2\right)}\)

\(\Leftrightarrow3x+6+2x+2=5x+4\)

\(\Leftrightarrow3x+2x-5x=-6-2+4\)

\(\Leftrightarrow0x=-4\)

=> PT vô nghiệm 

\(2;\frac{2}{3x-1}-\frac{15}{6x^2-x-1}=\frac{3}{2x-1}\)

\(\Leftrightarrow\frac{2\left(2x-1\right)}{\left(2x-1\right)\left(3x-1\right)}-\frac{15}{6x^2+3x-2x-1}=\frac{3\left(3x-1\right)}{\left(2x-1\right)\left(3x-1\right)}\)

\(\Leftrightarrow\frac{4x-2-15}{\left(2x-1\right)\left(3x-1\right)}=\frac{9x-3}{\left(2x-1\right)\left(3x-1\right)}\)

\(\Leftrightarrow4x-2-15=9x-3\)

\(\Leftrightarrow4x-9x=2+15-3\)

\(\Leftrightarrow-5x=14\)

.....

mấy cái này mẫu nào dài cậu phân tích ra : 

VD : câu  3 : \(3x^2-4x+1\)

\(=3x^2-3x-x+1\)

\(=3x\left(x-1\right)-\left(x-1\right)\)

\(=\left(3x-1\right)\left(x-1\right)\)

r bắt đầu giải PHương trình :)) Mấy câu còn lại tương tự 

4; \(\frac{5}{x-2}+\frac{2}{x+4}=\frac{3x}{x^2+2x-8}.\)

\(\Leftrightarrow\frac{5\left(x+4\right)}{\left(x-2\right)\left(x+4\right)}+\frac{2\left(x-2\right)}{\left(x-2\right)\left(x+4\right)}=\frac{3x}{\left(x-2\right)\left(x+4\right)}\)

\(\Leftrightarrow5x+20+2x-4=3x\)

\(\Leftrightarrow4x=-16\Leftrightarrow x=-2\left(TM\right)\)

KL ::

\(5;\frac{4}{x+6}+\frac{1}{x-3}=\frac{9}{x^2+3x-18}\)

\(\Leftrightarrow\frac{4\left(x-3\right)}{\left(x+6\right)\left(x-3\right)}+\frac{x+6}{\left(x-3\right)\left(x+6\right)}=\frac{9}{\left(x-3\right)\left(x+6\right)}\)

\(\Leftrightarrow4x+x=3+9-6\)

\(\Leftrightarrow5x=6\Leftrightarrow x=\frac{6}{5}\)

1: Ta có: \(\dfrac{x+4}{4}+\dfrac{3x-7}{5}=\dfrac{7x+2}{20}\)

\(\Leftrightarrow5x+20+12x-28=7x+2\)

\(\Leftrightarrow17x-7x=2+8=10\)

hay x=1

2: Ta có: \(\dfrac{x}{6}+\dfrac{1-3x}{9}=\dfrac{-x+1}{12}\)

\(\Leftrightarrow\dfrac{6x}{36}+\dfrac{4\left(1-3x\right)}{36}=\dfrac{3\left(-x+1\right)}{36}\)

\(\Leftrightarrow6x+4-12x=-3x+3\)

\(\Leftrightarrow-6x+3x=3-4\)

hay \(x=\dfrac{1}{3}\)

3: Ta có: \(\dfrac{x-3}{3}-\dfrac{x+2}{12}=\dfrac{2x-1}{4}\)

\(\Leftrightarrow4x-12-x-2=6x-3\)

\(\Leftrightarrow3x-14-6x+3=0\)

\(\Leftrightarrow-3x=11\)

hay \(x=-\dfrac{11}{3}\)

4: Ta có: \(\dfrac{x-2}{4}-\dfrac{2x+3}{3}=\dfrac{x+6}{12}\)

\(\Leftrightarrow3x-6-8x-12=x+6\)

\(\Leftrightarrow-5x-x=6+18\)

hay x=-4

5: Ta có: \(\dfrac{2x-1}{12}-\dfrac{3-x}{18}=\dfrac{-1}{36}\)

\(\Leftrightarrow6x-3+2x-6=-1\)

\(\Leftrightarrow8x=8\)

hay x=1

Tìm x:

1. 3x (2x + 3) - (2x + 5).(3x - 2) = 8

\(\Leftrightarrow6x^2+9x-6x^2+4x-15x+10=0 \)

\(\Leftrightarrow-2x+10=0\Leftrightarrow x=5\)

Vậy x = 5

2. 4x (x -1) - 3(x² - 5) -x² = (x - 3) - (x + 4)

\(\Leftrightarrow4x^2-4x-3x^2+15-x^2=x-3-x-4\)

\(\Leftrightarrow-4x+15=-7\)

\(\Leftrightarrow-4x=-22\Leftrightarrow x=\frac{11}{2}\)

Vậy x = \(\frac{11}{2}\)

3. 2 (3x -1) (2x +5) - 6 (2x - 1) (x + 2) = -6

\(\Leftrightarrow2\left(6x^2+15x-2x-5\right)-6\left(2x^2+4x-x-2\right)=-6\)

\(\Leftrightarrow12x^2+30x-4x-10-12x^2-24x+6x+12=-6\)

\(\Leftrightarrow8x=-8\Leftrightarrow x=-1\)

Vậy x = -1

4. 3 ( 2x - 1) (3x - 1) - (2x - 3) (9x - 1) - 3 = -3

\(\Leftrightarrow3\left(6x^2-2x-3x+1\right)-18x^2+2x+27x-3-3=-3\)

\(\Leftrightarrow18x^2-6x-9x+3-18x^2+2x+27x-6=-3\)

\(\Leftrightarrow14x=0\Leftrightarrow x=0\)

Vậy x = 0

5. (3x - 1) (2x + 7) - ( x + 1) (6x - 5) = (x + 2) - (x - 5)

\(\Leftrightarrow6x^2+21x-2x-7-6x^2+5x-6x+5=7\)

\(\Leftrightarrow18x=9\Leftrightarrow x=\frac{1}{2}\)

Vậy x = \(\frac{1}{2}\)

6. 3xy (x + y) - (x + y) (x² + y² + 2xy) + y³ = 27

\(\Leftrightarrow3x^2y+3xy^2-\left(x+y\right)^3+y^3=27\)

\(\Leftrightarrow3x^2y+3xy^2-x^3-y^3-3x^2y-3xy^2+y^3=27\)

\(\Leftrightarrow-x^3=27\)

\(\Leftrightarrow x=-3\)

Vậy x = -3

7. 3x (8x - 4) - 6x (4x - 3) = 30

\(\Leftrightarrow24x^2-12x-24x^2+12x=30\)

\(\Leftrightarrow0=30\) ( vô lý)

Vậy pt vô nghiệm

8. 3x (5 - 2x) + 2x (3x - 5) = 20

\(\Leftrightarrow15x-6x^2+6x^2-10x=20\)

\(\Leftrightarrow5x=20\Leftrightarrow x=4\)

Vậy x = 4

giúp mình bài ni với :3x^2(x+1)-5x(x+1)^2+4(x+1)