Question

Tim x: 

a) (2x - 1)^3 = 8

b) (x - 1)^x+2 = (x - 1)^x + 4

c) 3^x - 1 + 5 . 3^3x -1 =162

d) x - 0,75 : 0,5 = (1/2)^3 .(-1)^6

Answer 1

a, (2x-1)³=8

2x-1=2

2x=2+1

2x=3

x=1,5

Answer 2

a, \(\left(2x-1\right)^3=8\)

\(\Leftrightarrow\left(2x-1\right)^3=2^3\)

\(\Leftrightarrow2x-1=2\Leftrightarrow2x=3\Leftrightarrow x=\frac{3}{2}\)

b, \(\left(x-1\right)^x+2=\left(x-1\right)^x+4\)

\(\Leftrightarrow\left(x-1\right)^x+2-\left(x-1\right)^x-4=0\)

\(\Leftrightarrow-2\ne0\)=> vô nghiệm 

c, \(3^x-1+5.3^{3x}-1=162\)

Đề sai.