Đáp án: C

C

\(2\left(2x-1\right)^2=50\\ \Rightarrow\left(2x-1\right)^2=50:2=25\\ \Rightarrow\left(2x-1\right)^2=5^2\)

\(\Rightarrow\left[{}\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)

Đs...

`4(x-21)-2=50`

`4(x-21)=50+2=52`

`x-21=52:4=13`

`x=13+21=34`

$4(x-21)-2=50$

$4(x-21)=50+2=52$

$x-21=52:4=13$

$x=13+21=34$

    123x 456456 - 123123 x 456

= 123 x 456 x 1001 - 123 x456 x1001

= 0 

\(6.5.7+8.11=30.7+8.11=2.15.7+2.4.11=2.\left(15.7+4.11\right)⋮2\\ \Rightarrow Hợp.số\)

A = 6.5.7 + 8.11

6⋮ 2;  8⋮ 2 ⇔A ⋮2 ⇔  A  ⋮ 1; 2; A ⇔ A là hợp số 

Từ trang 1 đến trang 9 cần dùng: (9-1+1) x 1= 9(chữ số)

Từ trang 10 đến trang 99 cần dùng: (99-10+1) x 2 = 180(chữ số)

Số trang sách từ trang 100 trở đi: (582 - 9 - 180): 3 = 131(trang sách)

Quyển sách đó có: 9 + 90 + 131= 230 (trang sách)

Ai làm mình tick đúng nha

Ex 5 :

1 . My sister and I share same hobby . We often go fish on the weekend .

2.I like collecting  glass bottles .

3 . Minh think skating is more interesting than playing board games .

4 .Listen to music in my free time is my favourite hobby .

5 . I don't khow why does she collect pen

6 . In the future I will travel arond in Viet Nam 

Nhớ tick nhaaa