Question

Bài 1:Tìm x

a,(2,7-x)¹⁰=1

b,(x-2)³=32

c,2^2x-1=16

d,9^x.27^x=27

 

Answer 1

a: =>2,7-x=1 hoặc 2,7-x=-1

=>x=1,7 hoặc x=3,7

c:=>2x-1=4

=>2x=5

hay x=5/2

d: =>3^2xx3^3x=3³

=>5x=3

hay x=3/5

Answer 2

\(a,\left(2,7-x\right)^{10}=1\\ \Leftrightarrow\left(2,7-x\right)^{10}=\left(\pm1\right)^{10}\\ \Leftrightarrow\left[{}\begin{matrix}2,7-x=1\\2,7-x=-1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=1,7\\x=3,7\end{matrix}\right.\\c,2^{2x-1}=16\\ \Leftrightarrow2^{2x-1}=2^4\\ \Leftrightarrow2x-1=4\\ \Leftrightarrow x=\dfrac{5}{2}\\ 9^x\cdot27^x=27\\ \Leftrightarrow 3^{2x}\cdot3^{3x}=3^3\\ \Leftrightarrow3^{5x}=3^3\\ \Leftrightarrow x=\dfrac{3}{5}\)

Answer 3

a) \(\left(2,7-x\right)^{10}=1\)

`=>`\(\left[{}\begin{matrix}2,7-x=1\\2,7-x=-1\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=1,7\\x=3,7\end{matrix}\right.\)

b) \(\left(x-2\right)^3=32\)

Sai đề .-.

c) \(2^{2x-1}=16\)

\(2^{2x-1}=4^2\)

`=>`\(2x-1=4\)

`2x=4+1`

`2x=5`

`x=5:2`

`x=2,5`

d) \(9^x\cdot27^x=27\)

\(3^{2x}\cdot3^{3x}=3^3\)

\(3^{\left(2+3\right)x}=3^3\)

\(3^{5x}=3^3\)

\(5x=3\)

`x=3:5`

`x=3/5`