Question

Giúp mk vs ạ!!

2. 3^x + 3^x+2 =99

Answer 1

\(2.3^x+3^{x+2}=99\)

⇔ \(2.3^x+3^x.3^2=99\)

⇔ \(3^x.\left(2+3^2\right)=99\)

⇔ \(3^x.11=99\)

⇔ \(3^x=99:11\)

⇔ \(3^x=9\)

⇔ \(3^x=3^2\)

=> \(x=2\)

Vậy \(x=2.\)

Chúc bạn học tốt!

Answer 2

\(2.3^x+3^{x+2}=99\)

\(\Leftrightarrow2.3^x+3^x.3^2=99\)

\(\Leftrightarrow3^x.\left(2+3^2\right)=99\)

\(\Leftrightarrow3^x.11=99\)

\(\Leftrightarrow3^x=\frac{99}{11}\)

\(\Leftrightarrow3^x=9=3^2\)

\(\Leftrightarrow x=2\)

Vậy : \(x=2\)

Answer 3

\(2.3^x+3^{x+2}=99\)

\(\Leftrightarrow2.3^x+3^x+3^2=99\)

\(\Leftrightarrow2.3^x+9.3^x=99\)

\(\Leftrightarrow\left(2+9\right).3^x=99\)

\(\Leftrightarrow11.3^x=99\)

\(\Leftrightarrow3^x=9\)

\(\Leftrightarrow x=2\)