;-; truiii uiiii , cj cứ nghe câu này là chạy mất dép;-;

Câu đố đúng ko bn?

\(7.\)

\(a,2^x=16\)

\(\Rightarrow2^x=2^4\)

\(\Rightarrow x=4\)

Vậy \(x=4\)

\(b,4^x=64\)

\(\Rightarrow4^x=4^3\)

\(\Rightarrow x=3\)

Vậy \(x=3\)

\(c,15^x=225\)

\(\Rightarrow15^x=15^2\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

\(d,3^x.3=243\)

\(\Rightarrow3^x=243:3\)

\(\Rightarrow3^x=81\)

\(\Rightarrow3^x=3^4\)

\(\Rightarrow x=4\)

Vậy \(x=4\)

\(e,2^x.7=56\)

\(\Rightarrow2^x=56:7\)

\(\Rightarrow2^x=8\)

\(\Rightarrow2^x=2^3\)

\(\Rightarrow x=3\)

Vậy \(x=3\)

\(g,x^6:x^3=125\)

\(\Rightarrow x^{6-3}=125\)

\(\Rightarrow x^3=125\)

\(\Rightarrow x^3=5^3\)

\(\Rightarrow x=5\)

Vậy \(x=5\)

\(x:11+8712=8771\)

\(\Rightarrow x:11=8771-8712\)

\(\Rightarrow x:11=59\)

\(\Rightarrow x=59\times11\)

\(\Rightarrow x=649\)

$\color{#104E8B}{\textit{@Mi}}$$\color{#4682B4}{\textit{yu}}$
$\color{#4F94CD}{\textit{ki}}$

\(2^x+2^{x+2}=20\)

\(\Rightarrow2^x.1+2^x.4=20\)

\(\Rightarrow2^x.\left(1+4\right)=20\)

\(\Rightarrow2^x.5=20\)

\(\Rightarrow2^x=20:5\)

\(\Rightarrow2^x=4\)

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

\(\Rightarrow x=2\)

Vậy \(x=2\)

Ta có :

\(135=3^3\cdot5\)

\(225=3^2\cdot5^2\)

\(\RightarrowƯCLN\left(135;225\right)=3^2\cdot5=9\cdot5=45\)

Vậy \(ƯCLN\left(135;225\right)=45\)

\(2^{x+2}+2^{x+2}=20\) đề như thế này đúng ko?

\(B=\dfrac{1}{25\times27}+\dfrac{1}{27\times29}+\dfrac{1}{29\times31}+...+\dfrac{1}{93\times95}\)

\(B=\dfrac{1}{2}\times\left(\dfrac{1}{25\times27}+\dfrac{1}{27\times29}+\dfrac{1}{29\times31}+...+\dfrac{1}{93\times95}\right)\)

\(B=\dfrac{1}{2}\times\left(\dfrac{1}{25}-\dfrac{1}{27}+\dfrac{1}{27}-\dfrac{1}{29}+...+\dfrac{1}{93}-\dfrac{1}{95}\right)\)

\(B=\dfrac{1}{2}\times\left(\dfrac{1}{25}-\dfrac{1}{95}\right)\)

\(B=\dfrac{1}{2}\times\left(\dfrac{95}{2375}-\dfrac{25}{2375}\right)\)

\(B=\dfrac{1}{2}\times\dfrac{14}{475}\)

\(B=1\times\dfrac{7}{475}\)

\(B=\dfrac{7}{475}\)

\(890-123=767\)

Em viết lại đề bài bằng biểu tượng Σ này nhé , chứ chị đọc chị chả hiểu cái gì cả!