Question

Answer 1

B

Answer 2

B

Answer 3

x = 3

Answer 4

`3(x+2)^2 - 5^2 = 2 . 5^2`.

`-> 3x^2 + 12x + 12 - 25 = 50`.

`-> 3x^2 + 12x - 63 = 0`.

`-> x^2 + 4x - 21 = 0`.

`-> (x+2)^2 = 5^2`.

`->` \(\left[{}\begin{matrix}x+2=-5\\x+2=5\end{matrix}\right.\)

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

Mà `x in NN`.

`-> x = 3.`.

`-> B`

Answer 5

B