Question

Tim x, biet:

a)\(3^{x-2}+3^{x-5}=252\)       b) \(\left(\frac{3}{4}-x\right)^2=\frac{25}{36}\)   

c) \(|2015x-1|-|-2015|=-2014\)

Ai nhanh mik tick!!!

Answer 1

Câu a bn cứ phân tích 3^x-2 + 3^x-5 ra 3^x : 3² + 3^x : 3⁵ là ra nhé!

b, \(\left(\frac{3}{4}-x\right)^2=\frac{25}{36}\)

Ta thấy: \(\frac{25}{36}=\left(\frac{5}{6}\right)^2\Rightarrow\left(\frac{3}{4}-x\right)^2=\left(\frac{5}{6}\right)^2\Rightarrow\frac{3}{4}-x=\frac{5}{6}\)

\(\Rightarrow x=\frac{3}{4}-\frac{5}{6}=\frac{9}{12}-\frac{10}{12}=\frac{-1}{12}\)

c, \(|2015x-1|-|-2015|=-2014\)

\(\Rightarrow|2015x-1|-2015=-2014\)

\(\Rightarrow|2015x-1|=-2014+2015=1\)

Bn cứ đưa ra 2 trường hợp \(2015x-1=1\)và \(2015x-1=-1\) là được nhé!

Answer 2

Ban co the lam chi tiet phan a giup mik dc ko?