có ai biết làm bài nầy không giúp mk vs mk đg cần rất rất gấp mong các bn giúp cho
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Những câu hỏi liên quan
9 tháng 9 2021
\(3,\\ a,\dfrac{\left(1+\sqrt{x}\right)^2-4\sqrt{x}}{1-\sqrt{x}}\\ =\dfrac{\sqrt{x}-2\sqrt{x}+1}{1-\sqrt{x}}=\dfrac{\left(1-\sqrt{x}\right)^2}{1-\sqrt{x}}=1-\sqrt{x}=1-\sqrt{2}\)
\(b,\dfrac{\left(\sqrt{x}-\sqrt{y}\right)^2+4\sqrt{xy}}{1+\sqrt{xy}}\\ =\dfrac{x+2\sqrt{xy}+y}{1+\sqrt{xy}}=\dfrac{\left(\sqrt{x}+\sqrt{y}\right)^2}{1+\sqrt{xy}}\\ =\dfrac{\left(\sqrt{2}+\sqrt{3}\right)^2}{1+\sqrt{6}}=\dfrac{5+2\sqrt{6}}{1+\sqrt{6}}\\ =\dfrac{\left(5+2\sqrt{6}\right)\left(\sqrt{6}-1\right)}{5}\\ =\dfrac{3\sqrt{6}+7}{5}\)
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17 tháng 9 2021
bài 1
\(\widehat{B}=90-\widehat{C}=90-30=60\)
\(sinC=\dfrac{AB}{BC}\Rightarrow BC=\dfrac{AB}{sinC}=\dfrac{30}{sin30}=60\)
áp dụng pytago vào \(\Delta ABC\)
\(AC=\sqrt{BC^2-AB^2}\)=\(\sqrt{60^2-30^2}\)=\(30\sqrt{3}\)=51,96
bài 2
\(\widehat{B}=90-\widehat{C}=90-30=60\)
\(sinC=\dfrac{AB}{BC}\Rightarrow AB=sinC.BC=sin30.5=2,5\)
áp
17 tháng 9 2021
áp dụng pytago vào \(\Delta ABC\)
\(AC=\sqrt{BC^2-AB^2}=\sqrt{5^2-2,5^2}\)=4,33
bài 3
\(\widehat{E}=90-\widehat{F}=90-47=43\)
\(sinF=\dfrac{ED}{EF}\Rightarrow EF=\dfrac{ED}{sinF}=\dfrac{9}{sin47}=12,31\)
áp dụng pytago vào \(\Delta DEF\)
\(DF=\sqrt{EF^2-ED^2}=\sqrt{12,31^2-9^2}\)=8,4
bài 4
áp dụng pytago vào \(\Delta ABC\)
\(AB=\sqrt{BC^2-AC^2}=\sqrt{32^2-27^2}=17,18\)
\(sinB=\dfrac{AC}{BC}=\dfrac{27}{32}\Rightarrow\widehat{B}=57\)
\(\widehat{C}=90-\widehat{B}=90-57=33\)
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Đỗ Thanh Hải
CTVVIP
12 tháng 9 2021
1 was arrested before the garden by the boy yesterday
2 his cats taken care of carefully by Jack everyday
3 Has the country been protected from Covid-19 successfully
4 is reported that the man is running out of money
is reported to be running out of money\
5 has been said that the thief got out of the prison
has been said to have got out of the prison
6 was thought that Mary had turned down the job
Mary was thought to have turned down the job
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Đỗ Thanh Hải
CTVVIP
14 tháng 9 2021
1 knowing the answer, they told us
2 the unique handicraft, we didn't like it
3 We looked into these machines so that we could find out the method
We looked into these machines so as to find out the method
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5 In order to choose the best chair, Linda looked through this catalouge
6 is not as dirty as this one
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A dog runs more slowly than a horse
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10 No one in my family talks as politely as Linda
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Đỗ Thanh Hải
CTVVIP
11 tháng 9 2021
1 My parents go shopping twice a week
2 Hoa's house has a balcony
3 My brother usually plays badminton with his friends
4 My favorite book is Tam and Cam. What is yours?
5 There are 10 pencil cases on the table
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