Cho tứ giác ABCD, kéo dài AB và CD cắt nhau tại E, kéo dài AB và BC cắt nhau tại F. Phân giác góc E và góc F cắt nhau tại O.CMR: Góc EOF= (góc ABC + Góc D) / 2

3/a)\(M\left(x\right)=\frac{1}{2}x^2-3x-x^3+3\)

\(=-x^3+\frac{1}{2}x^2-3x+3\)

\(N\left(x\right)=-4x+x^2+\frac{1}{2}x^3+6\)

\(=\frac{1}{2}x^3+x^2-4x^3+6\)

b)Ta có:\(\text{A}\left(x\right)=M\left(x\right)-N\left(x\right)\)

hay \(\text{A}\left(x\right)=\left(-x^3+\frac{1}{2}x^2-3x+3\right)-\left(\frac{1}{2}x^3+x^2-4x+6\right)\)

\(=-x^3+\frac{1}{2}x^2-3x+3-\frac{1}{2}x^3-x^2+4x-6\)

\(=-\frac{3}{2}x^3-\frac{1}{2}x^2+x-3\)

Đặt\(\text{A}\left(x\right)=0\)

\(\Rightarrow-\frac{3}{2}x^3-\frac{1}{2}x^2+x-3=0\)

\(-\frac{3}{2}x^3-\frac{1}{2}x^2=-x+3\)

\(-2\left(x^3-x^2\right)=-x+3\)

\(x^3-x^2+x=3+2=5\)

\(x^2=5\)

\(\Rightarrow x=\sqrt{5}\)

Vậy \(\text{A}\left(x\right)\) có 1 nghiệm là \(\sqrt{5}\)

Cho đa thức:M(x)=1/2x^2-3x-x^3+3
N(x)=-4x+x^2+1/2x^3+6
a/Sắp xếp các hạng tử của mỗi đa thức trên theo lũy thừa giảm dần của biến.
b/Tìm nghiệm của đa thức A(x), biết A(x)=M(x)-N(x)

Use the proper form or tense of the verbs in parentheses to fill in each blank.
1.Cheese...............................(make)from milk.
2.The question is difficult.................................(answer)
3.While I was on vocation,my camera.........................(steal)from my hotel.
4.Hurry up!Everybody...................(wait)for you.
5.They(search).........................................................the victims when we came to the palace of accident.
6.His wounds........................................so carefully that he got well soon.(treat).
7.Would you mind..............................................the volume of your radio?It's midnight.(adjust)
8.She has promised...................harder.(work)
9.If Trang had an alarm clock,she(arrive)..........................to school on time.
10.The doctor advised me(go)..................jogging every morning.

1.Jack is ill so he can't come to the English club.
If...................................................................................................................
2.Nam gets good marks because he always tries his best to study.
If...................................................................................................................

3.Save energy and you'll contribute to saving our earth.
If...................................................................................................................

1.The scientist said:"Cloning will become more popular in next century"
_The scientist..............................................................................................
2.Dr.Nelson said to me,"Every home will have at least one robot to perform any boring task"
_Dr.Nelson...................................................................................................

Give the correct form of the words given to complete the sentences.

1.The air in the city is very.........(pollute)

Cho đa thức f(x)=ax+b(a\(\ne\)).Cho biết f(1)=-1 và f(-1)=1.Tìm hệ số a và b.

Cho \(B=\frac{8-x}{x-3}\left(x\in Z\right)\)

Tìm \(x\in Z\) để

a/B có giá trị nguyên
b/B có GTNN

Tìm a,b,c biết A=0 biết A=(-2a^2b^3)^10+(3b^2c^4)^15