\(=x^5y^4-x^3y^7-x^7y^3+x^3y^7^{ }\)
=x⁵y⁴-x⁷y³

bất thường

267

bài 3 
d) sin²a+cos²a=1
\(\left(\dfrac{AC}{BC}\right)^2+\left(\dfrac{AB}{BC}\right)^2=\dfrac{AC^2}{BC^2}+\dfrac{AB^2}{BC^2}=\dfrac{BC^2}{BC^2}=1\)
b)
cot a =\(\dfrac{cosa}{sina}\)
\(\dfrac{cosa}{sina}\)=\(\dfrac{AB}{\dfrac{BC}{\dfrac{AC}{BC}}}=\dfrac{AB}{AC}=cota\)

1, do you live,live
2,are he doing , watering
3,does she do , is
4, are
5, is playing, is playing 
6, are watching
7, go,have,am,visit
8, Does your father go
9,does your sister go
10,do they get up
11,do they do
12, have
13,is
14,likes
15, is calling
16,am listening

1, I wish I knew more people
2, I wish I had a key
3,I wish Ann was here
4, I wsh it wan't cold
5, wish I didn't live in a big city
6, I wish I couldn't go to the party
7, I wish I hadn't to work tomorrow
8, I wish I got good marks
9, I wish i was lying on the beatiful sunny beach
 

1 met
2,have known
3, wil
4, buy
5,had gone
6,travels

=\(\dfrac{2\sqrt{5}\left(\sqrt{5}+\sqrt{2}\right)}{\left(\sqrt{5}+\sqrt{2}\right)}-\dfrac{8\left(\sqrt{5}+1\right)}{\left(\sqrt{5}-1\right)\left(\sqrt{5}+1\right)}\)
\(=2\sqrt{5}-\dfrac{8\left(\sqrt{5}+1\right)}{4}\)
\(=2\sqrt{5}-2\left(\sqrt{5}+1\right)\)
\(=2\sqrt{5}-2\sqrt{5}-2\)
=-2
 

\(a.\sqrt{x-1}+\sqrt{4x-4}-\sqrt{25x-25}+2=0\)( x lớn hơn hoặc =1)
\(\sqrt{x-1}+\sqrt{4\left(x-1\right)}-\sqrt{25\left(x-1\right)}\)+2=0
\(\sqrt{x-1}\left(1+\sqrt{4}-\sqrt{25}\right)=-2\)
\(\sqrt{x-1}\left(1+2-5\right)=-2\)
\(\sqrt{x-1}.\left(-2\right)=-2\)
\(\sqrt{x-1}=-2.2\)
\(\sqrt{x-1}-4\)(ko thỏa mãn)
b)
\(\dfrac{1}{2}\sqrt{x-1}-\dfrac{3}{2}\sqrt{9x-9}+24\sqrt{\dfrac{x-1}{64}}=-17\)
\(\dfrac{1}{2}\sqrt{x-1}-\dfrac{3}{2}\sqrt{9\left(x-1\right)}+24\dfrac{\sqrt{x-1}}{8}=-17\)
\(\dfrac{1}{2}\sqrt{x-1}-\dfrac{3}{2}.3\sqrt{x-1}+3\sqrt{x-1}=-17\)
\(\dfrac{1}{2}\sqrt{x-1}-\dfrac{9}{2}\sqrt{x-1}+3\sqrt{x-1}=-17\)
\(\left(\dfrac{1}{2}-\dfrac{9}{2}+3\right)\sqrt{x-1}=-17\)
\(7\sqrt{x-1}=-17\)
\(\sqrt{x-1}=-\dfrac{17}{7}\)(ko thỏa mãn căn bậc 2 ko có số âm)

1h
2j
3c
4e
5g
6a
7d
8i
9f
10b