lion

elephant

tiger

fox

bear

bird 

aunt

turtle 

kangaroo

.....

1:

(+) Everyone likes music

(-) Everyone doens't like music

(?) Does everyone like music ?

2: 

(+) We have that food sofar

(-) We don't have that food sofar

(?): Do you have that food sofar ?

a) Có: BC = BF (GT)

=> Tam giác BCF cân tại B

\(\Rightarrow2\widehat{F}=180^0-\widehat{CBF}\left(1\right)\)

Có: \(\widehat{ABC}=180^0-\widehat{CBF}\) (kề bù) (2)

Từ (1) và (2) => \(\widehat{ABC}=2\widehat{F}=2.\widehat{BCF}\)

b) \(\widehat{ABC}=2\widehat{F}=2.\widehat{BCF}\) (cmt)

Mà: \(\widehat{ABC}=2.\widehat{MBC}\)

=> Góc MBC = Góc BCF 

Mà 2 góc này là 2 góc so le trong

=> BM // CF

Bài nào em nhỉ ?

P/s: Ngắn thôi nha nhiều là bj xóa đó!

\(0,05+5-\dfrac{1}{20}=0,05+5-0,05=5\)

\(\dfrac{6}{15}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{2}{16}=\dfrac{2}{.5}-\dfrac{7}{8}+3+\dfrac{3}{5}-\dfrac{1}{8}=1-1+3=3\)

BT A - B hay A.B vậy bn ?

a) a ≠ 1; a ≥ 0

\(\dfrac{a-5\sqrt{a}+4}{a-1}=\dfrac{a-\sqrt{a}-4\sqrt{a}+4}{a-1}=\dfrac{\sqrt{a}\left(\sqrt{a}-1\right)-4\left(\sqrt{a}-1\right)}{a-1}=\dfrac{\left(\sqrt{a}-1\right)\left(\sqrt{a}-4\right)}{\left(\sqrt{a}-1\right)\left(\sqrt{a}+1\right)}=\dfrac{\sqrt{a}-4}{\sqrt{a}+1}\)

b) a ≥ 0; \(x\ne\pm\sqrt{3}\)

\(\dfrac{\sqrt{x^2+2\sqrt{3x}+3}}{x^2-3}=\dfrac{x+\sqrt{3}}{\left(x+\sqrt{3}\right)\left(x-\sqrt{3}\right)}=\dfrac{1}{x-\sqrt{3}}\)