Question

[Lưu Đào Đại Quang]

a)x²=x³
b)3^x-1=27
c)3^x+1=9

Answer 1

[✎﹏Kim Kim✧❤‿✶🌈(*•.¸♡ţęąɱ ƒŗęę ƒįŗę...]

a) xem lại đề

b) 3^x-1=27

=>3^x-1=3³

=>x-1=3

=>x=3+1

=>x=4

c)3^x+1=9

=>3^x+1=3²

=>x+1=2

=>x=2-1

=>x=1

Answer 2

[Lê Minh Quang]

a) x²=x³

⇒ x²-x³=0

⇒ x²-x².x=0

⇒ x².(x+1)=0

⇒\(\left\{{}\begin{matrix}\text{x}^2=0\\\text{x}+1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\text{x}=0\\\text{x}=0+1=1\end{matrix}\right.\)

⇒ \(\text{x}\in\left\{0;1\right\}\)

b) 3^x-1=27

⇒ 3^x-1=3³

⇒ x-1=3

⇒ x= 3+1=4

c) 3^x+1=9

⇒ 3^x+1= 3³

⇒ x+1=3

⇒ x=3-1=2