Question

3.5^2x-6​=75

Answer 1

\(3.5^{2x-6}=75\)

\(5^{2x-6}=75:3\)

\(5^{2x-6}=25\)

\(5^{2x-6}=5^2\)

\(\Rightarrow2x-6=2\)

\(2x=8\)

\(x=4\)

Answer 2

\(3.5^{2x-6}=75\)

\(5^{2x-6}=75\div3\)

\(5^{2x-6}=25\)

\(5^{2x-6}=5^2\)

\(\Rightarrow2x-6=2\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=4\)

Answer 3

3 . 5^{2x - 6} = 75

5^{2x - 6} = 75 : 3

5^{2x - 6} = 25

 5^{2x - 6} = 5²

=> 2x - 6 = 2

=> 2x = 8

=> x = 4

Vậy x = 4

Answer 4

Ta có: \(3.5^{2x}-6=75\)

\(\Rightarrow3.5^{2x}=75+6=81\)

\(\Rightarrow5^{2x}=81:3=27\)

Mà \(27=3^3\)

=> \(5^{2x}=3^3\) ( không hợp lí)

Vậy \(x\in\theta\)