để \(\frac{n^2+n-5}{n+2}\)nguyên \(\Leftrightarrow n^2+n-5⋮n+2\)

                                            \(\Leftrightarrow n^2+2n-n-5⋮n+2\)

                                            \(\Leftrightarrow n.\left(n+2\right)-n-5⋮n+2\)

                                     mà         \(n.\left(n+2\right)⋮n+2\)

\(\Rightarrow n-5⋮n+2\)

\(\Rightarrow n+2-7⋮n+2\)

 mà \(n+2⋮n+2\)

\(\Rightarrow7⋮n+2\)

em tự làm típ nhé 

Điều kiện xác định:\(n\ne-2\)

Ta có:

\(\frac{n^2+n-5}{n+2}=\left(n-1\right)-\frac{3}{n+2}\) (chia đa thức, có \(-\frac{3}{n+2}\)vì chia dư -3)

Để \(\frac{n^2+n-5}{n+2}\) là số nguyên

=> \(3⋮n+2\)

=>\(\left(n+2\right)\inƯ\left(3\right)\)

=>\(\left(n+2\right)\in\left\{-3;-1;1;3\right\};n\in Z\)

=>\(n\in\left\{-5;-3;-1;1\right\}\)

Cũng trong sáng như vậy nước biển thêm xanh biếc đậm Đà hơn hết cả mọi khi là so sánh

Aggwehvff

\(\frac{-1}{2}+\frac{3}{21}+\frac{-2}{6}+\frac{-5}{30}\)

\(\frac{-1}{2}+\frac{1}{7}+\frac{-1}{3}+\frac{-1}{6}\)

\(\frac{-21}{42}+\frac{6}{42}+\frac{-14}{42}+\frac{-7}{42}\)

\(\frac{-36}{42}=-\frac{6}{7}\)

\(\left(6-2\frac{4}{5}\right).3\frac{1}{8}-1\frac{3}{5}:\frac{1}{4}\)

\(=\left(6-\frac{14}{5}\right).\frac{25}{8}-\frac{8}{5}:\frac{1}{4}\)

\(=\frac{16}{5}.\frac{25}{8}-\frac{32}{5}\)

\(=10-\frac{32}{5}\)

\(=\frac{18}{5}\)

sorry, mik ko biết vẽ trên này thế nào

b. Ta thấy: OD là tia đối của tia OB

=> \(\widehat{BOD}\)là góc bẹt =  \(^{180^0}\)

=> \(\widehat{DOC}+\widehat{COB}=\widehat{DOB}\)

=> Góc kề bù với \(\widehat{BOC}\)là \(\widehat{DOC}\)

=> \(\widehat{DOC}=\widehat{DOB}-\widehat{COB}\)

Mà: \(\widehat{COB}=\widehat{COA}-\widehat{BOA}\)

=>\(\widehat{COB}=80^0-35^0\)

=>\(\widehat{COB}=45^0\)

Thay:\(\widehat{DOB}=180^0,\widehat{COB}=45^0\)

=> \(\widehat{DOC}=180^0-45^0\)

=>\(\widehat{DOC}=135^0\)

1. I (have) ____will have_____ a UFO in the future.

2. We (be) ___have been______ to Ha Noi many times.

3. I (not go) _______didn't go_________ to school last Sunday.

4. Yesterday my friends and I (play)_______played________ sports in the school yard.

5. Peolple might (live) ______live______ on the moon

Give the corrcet form of the verbs:

1. I (have) ___will have______ a UFO in the future.

2. We (be) ____have been_____ to Ha Noi many times.

3. I (not go) ________didn't go ________ to school last Sunday.

4. Yesterday my friends and I (play)______played_________ sports in the school yard.

5. Peolple might (live) ______live______ on the moon.

1 Robots/not only/talk/people/but/understand/what they think.

\(\Rightarrow\) Robots don't only talk to people but also understand what they think.

2. Robots/recognise/our voices/faces/they/not/ think//human.

\(\Rightarrow\) Robots can recognise our voices and faces but they don't think they human.

3.You/think/robots/build house/sea/us ?

\(\Rightarrow\) Do you think robots can build house by the sea for us?

4 i/agree/you/that/life/more comfortable/future .

\(\Rightarrow\)I agree with you that life will mỏe comfortable in the future.

5.More people/lose/job/robots/do/many kinds/jobs.

\(\Rightarrow\)More people lose job but robots can do many kinds of jobs.

sai đề ko bạn ?