Question

tìm x, biết:

a. (x mũ 2 - 1) + 3 = 11

b. 3 mũ x trừ mũ 1 = 27

c. 5 mũ x + mũ 2 = 125

Answer 1

a: =>x²+2=11

=>x²=9

=>x=3 hoặc x=-3

b: =>x-1=3

hay x=4

c: =>x+2=3

=>x=1

Answer 2

`a) (x^2 -1)+3 =11`

`<=> x^2 - 1 = 11-3 =8`

`=> x^2 = 8+1=9`

`<=>`\(\left[{}\begin{matrix}x=\sqrt{9}=3\\x=-\sqrt{9}=-3\end{matrix}\right.\)

`b) 3^(x-1) =27`

`<=> 3^(x-1) = 3^3`

`=> x-1=3`

`=> x=3+1=4`

`c) 5^(x+2) =125`

`<=> 5^(x+2) = 5^3`

`=> x+2=3`

`=> x=3-2 =1`

Answer 3

a) (x² - 1) + 3 = 11

x² - 1 = 11 - 3

x² - 1 = 8

x² = 9

x = 3 hoặc x = -3

Answer 4

b) x - 1 = 3

x = 3 + 1

x = 4

Answer 5

c) x + 2 = 3

x = 3 - 1

x = 2