Giúp em phần B với ạ
K
Khách
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4 tháng 9 2021
b) \(\sqrt{29-12\sqrt{5}}+\sqrt{45-20\sqrt{5}}=\sqrt{\left(2\sqrt{5}-3\right)^2}+\sqrt{\left(5-2\sqrt{5}\right)^2}=2\sqrt{5}-3+5-2\sqrt{5}=2\)
h) \(\left(\sqrt{10}-\sqrt{6}\right)\sqrt{4+\sqrt{15}}=\left(\sqrt{10}-\sqrt{6}\right)\sqrt{\left(\sqrt{\dfrac{5}{2}}+\sqrt{\dfrac{3}{2}}\right)^2}=\left(\sqrt{10}-\sqrt{6}\right)\left(\sqrt{\dfrac{5}{2}}+\sqrt{\dfrac{3}{2}}\right)=\sqrt{25}+\sqrt{15}-\sqrt{15}-\sqrt{9}=5-3=2\)
4 tháng 9 2021
h: Ta có: \(\left(\sqrt{10}-\sqrt{6}\right)\cdot\sqrt{4+\sqrt{15}}\)
\(=\left(\sqrt{5}-\sqrt{3}\right)\left(\sqrt{5}+\sqrt{3}\right)\)
=5-3=2
NN
2
NV
Nguyễn Việt Lâm
Giáo viên
25 tháng 10 2021
Chọn 4 cuốn sách bất kì: \(C_{12}^4=495\) cách
Chọn 4 cuốn sách sao cho có đủ 3 môn:
\(C_5^1.C_4^1.C_3^1=60\) cách
Chọn 4 cuốn sao cho không thuộc quá 2 môn:
\(495-60=435\) cách
22 tháng 8 2021
Bài 2:
b: Ta có: \(B=\dfrac{15-5\sqrt{x}}{x-5\sqrt{x}+6}+\dfrac{\sqrt{x}+3}{\sqrt{x}-2}\)
\(=\dfrac{-5\left(\sqrt{x}-3\right)}{\left(\sqrt{x}-3\right)\left(\sqrt{x}-2\right)}+\dfrac{\sqrt{x}+3}{\sqrt{x}-2}\)
\(=\dfrac{\sqrt{x}-2}{\sqrt{x}-2}=1\)
MD
1
KY
6 tháng 7 2021
He is widely regarded as the best man for the job.
The suspect could not account for the sand in his boots
sally came up with the best solution.
You need to make allowances for the fact that he hasn't spoken French for years.
It was inevitable that he would fail his exams.
2) Will you study in another country ?
3)Will the class finish at 11 o'clock ?
4) Will you learn to ride a motor bike?
5)Will it be warm and sunny tomorrow ?
6)Will you and your family abroad thí summer?
7)Will you be rich and famous ?
2. Will you study in another country?
Yes, I will./ No, I won't.
3. Will the class finish at 11 o'clock?
Yes, it will./ No, it won't.
4. Will you learn to ride a motorbike?
Yes, I will./ No, I won't.
5. Will it be warm and sunny tomorrow?
Yes, it will./ No, it won't.
6. Will you and your family go abroad this summer?
Yes, we will./ No, we won't.
7. Will you be rich and famous?
Yes, I will./ No, I won't.