a)=>3x=33

=>x=11

b)x²⁰⁰=x

=>x²⁰⁰-x=0

=>x(x¹⁹⁹-1)=0=>x=0 hoặc x=1

c)=>1170:(x-13)=339-300=39

=>x-13=1170:39=30

=>x=43

d)=>7x=28

=>x=4

\(\frac{4x}{28}=\frac{13}{19}+\frac{8}{15}\)

\(\frac{x}{7}=\frac{347}{285}\)

\(x=\frac{347}{285}:7\)

\(x=\frac{2429}{285}\)

\(\frac{4x}{28}=\frac{13}{19}+\frac{8}{15}\)

\(\Rightarrow\frac{4x}{28}=\frac{347}{285}\)

\(\Rightarrow4x=\frac{28.347}{285}=\frac{9716}{285}\)

\(\Rightarrow x=\frac{9716}{285}:4=\frac{2429}{285}\)

bạn làm đúng rồi nhé

chúc bạn học tốt@

bạn ơi có ai trả lời đâu mà bạn bảo đúng thế bạn

a) \(\left(4x-13\right)^4+4^3=145\)

\(\Rightarrow\left(4x-13\right)^4+64=145\)

\(\Rightarrow\left(4x-13\right)^4=81\)

\(\Rightarrow4x-13=\pm3\)

+) \(4x-13=3\)

\(\Rightarrow4x=16\)

\(\Rightarrow x=4\)

+) \(4x-13=-3\)

\(\Rightarrow4x=10\)

\(\Rightarrow x=\frac{5}{2}\)

Vậy \(x=4\) hoặc \(x=\frac{5}{2}\)

b) \(3^{x+2}-3^x=72\)

\(\Rightarrow3^x.3^2-3^x=72\)

\(\Rightarrow3^x.\left(3^2-1\right)=72\)

\(\Rightarrow3^x.8=72\)

\(\Rightarrow3^x=9\)

\(\Rightarrow3^x=3^2\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

c) \(2^{x+2}-2^{x-1}=224\)

\(\Rightarrow2^{x-1+3}-2^{x-1}=224\)

\(\Rightarrow2^{x-1}.2^3-2^{x-1}=224\)

\(\Rightarrow2^{x-1}.\left(2^3-1\right)=224\)

\(\Rightarrow2^{x-1}.7=224\)

\(\Rightarrow2^{x-1}=32\)

\(\Rightarrow2^{x-1}=2^5\)

\(\Rightarrow x-1=5\)

\(\Rightarrow x=6\)

Vậy x = 6

(1) ↔ (4x - 3)⁴ = 81 ↔ (4x - 3)⁴ = 3⁴

↔ 4x - 3 = 3 hoặc 4x - 3 = -3 ↔ x = 3/2 hoặc x = 0

(2) ↔ 9*3^x - 3^x = 72 ↔ 8*3^x = 72 ↔ 3^x = 9 ↔ x = 2

(3) ↔ 8*2^x-1 - 2^x-1 = 224 ↔ 7*2^x-1 =224

↔ 2^x-1 = 32 ↔ x = 6

x=4/5

Bài 1 : 

\(a)\)Ta có : 

\(13< 4x\le21\)

\(\Leftrightarrow\)\(\frac{13}{4}< \frac{4x}{4}< \frac{21}{4}\)

\(\Leftrightarrow\)\(3,25< x< 5,25\)

\(\Rightarrow\)\(x=5\)

\(\Rightarrow\)\(A=\left\{5\right\}\)

Các tập hợp con của tập hợp \(A\) : \(B=\left\{\varnothing\right\}\)\(;\)\(C=\left\{5\right\}\)

\(b)\) Ta có : \(x=ab\)

\(\Rightarrow\)\(x=3.2=6\)

Hoặc \(x=3.6=18\)

Hoặc \(x=9.2=18\)

Hoặc \(x=9.6=54\)

Vậy \(C=\left\{6;18;54\right\}\)

Chúc bạn học tốt ~ 

Bài 5 : 

Ta có : 

\(\overline{2x3y}\) chia hết cho 2 và 5 \(\Rightarrow\)\(y=0\)

Lại có : \(\overline{2x3y}\) chia 9 dư 1 \(\Rightarrow\)\(2+x+3+y-1⋮9\)

\(\Leftrightarrow\)\(2+x+3+0-1⋮9\)

\(\Leftrightarrow\)\(x+4⋮9\)

Mà \(0\le x\le9\) nên \(x=5\)

Vậy \(x=5\) và \(y=0\)

Chúc bạn học tốt ~ 

\(\frac{12}{x}\)+ 9 = 45

\(\frac{12}{x}\) = 36

x = \(\frac{12}{36}\)= 1/3

b) 5x + 8- 4x = 72

   (5x-4x) +8 = 72

   x + 8 = 72

 x = 72-8

x= 64

\(a,\frac{12}{x}+9=45\)

\(\Rightarrow\frac{12}{x}=45-9=36\)

\(\Rightarrow x=12:36=\frac{1}{3}\)

\(b,5x+8-4x=72\)

\(\Rightarrow5x-4x=72-8\)

\(\Rightarrow x=64\)

\(8-12x+6x^2-x^3\)

\(=\left(2-x\right)^3\)

\(125x^3-75x^2+15x-1\)

\(=\left(5x-1\right)^3\)

\(x^2-xz-9y^2+3yz\)

\(=\left(x-3y\right)\left(x+3y\right)-z\left(x-3y\right)\)

\(=\left(x-3y\right)\left(x+3y-z\right)\)

\(x^3-x^2-5x+125\)

\(=\left(x+5\right)\left(x^2-5x+25\right)-x\left(x+5\right)\)

\(=\left(x+5\right)\left(x^2-5x+25-x\right)\)

\(=\left(x+5\right)\left(x^2-6x+25\right)\)

\(x^3+2x^2-6x-27\)

\(=x^3+5x^2+9x-3x^2-15x-27\)

\(=x\left(x^2+5x+9\right)-3\left(x^2+5x+9\right)\)

\(=\left(x-3\right)\left(x^2+5x+9\right)\)

\(12x^3+4x^2-27x-9\)

\(=4x^2\left(3x+1\right)-9\left(3x+1\right)\)

\(=\left(3x+1\right)\left(4x^2-9\right)\)

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

\(4x^4+4x^3-x^2-x\)

\(=4x^3\left(x+1\right)-x\left(x+1\right)\)

\(=x\left(x+1\right)\left(4x^2-1\right)\)

\(=x\left(x+1\right)\left(2x-1\right)\left(2x+1\right)\)

Là 00000000000000