HOC24
Lớp học
Môn học
Chủ đề / Chương
Bài học
1. Nam is (old)...........older..............than Ba
2. This house is (big)......bigger........than mine
3. He is ( intelligent).......more intelligent.......than us
4. She is (tall).....the tallest.......in her group
5. This shirt (expensive)...........is the most expensive............ of all
6.Lan studies math (well)..........better............than you. (câu này đề phải là studies)
7. He has (many)......more......books than me
8. She is (beautiful).......the most beautiful........in her class
9. She studies English (badly)........the worst.........in her group
10. His house is (far)....further.........than mine.
1. He works faster than his brother
His brother doesn't work as fast as his brother. / work faster than his brother.
2. No one in my class is taller than Nam
Nam is the tallest student in my class.
3. Hoa has more friends than I do
I don't have as many friends as Hoa. / have more friends than Hoa.
4. What does Mr. An do?
What is Mr. An job?
Ta có: a2-(a-1)(a+1)
= a2-(a2-a+a-1)
= a2-a2+a-a+1
=1
Vậy a2-(a-1)(a+1)=1 (đpcm)
Ta có: (x-7)(8+x)=0
=> x-7=0 hoặc 8+x=0
=> x=7 hoặc x=-8
Ta có: (x-5)(x+6)=0
=> x-5=0 hoặc x+6=0
=> x=5 hoặc x=-6
a) Ta có: n+4 chia hết cho n+1
n+1 chia hết cho n+1
=> n+4-n-1 chia hết cho n+1
=> 3 chia hết cho n+1
=> n+1 thuộc ước của 3
=> n+1 ={-3;3;-1;1}
=> n+1={-4;2;-2;0}
(x2- 7).(x2-49)<0
TH1: \(\Rightarrow\left\{{}\begin{matrix}x^2-7< 0\\x^2-49>0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x^2< 7\\x^2>49\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x< 2\\x>7\end{matrix}\right.\)
TH2: \(\Rightarrow\left\{{}\begin{matrix}x^2-7>0\\x^2-49< 0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x^2>7\\x^2< 49\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}x>3\\x< 7\end{matrix}\right.\)
Vậy x<2 và x>7 hoặc x>3 và x<7
(1890-19-5)-(19-5-1890)
= 1890-19-5-19+5+1890
= 3742