tìm GTLN

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

cho bt với x≥0 , x≠9

P=\(\left(\frac{2\sqrt{2}}{\sqrt{x}+3}\frac{\sqrt{x}}{\sqrt{x}-3}-\frac{3x+3}{x-9}\right):\left(\frac{2\sqrt{x}-2}{\sqrt{x}-3}-1\right)\)

a) rút gọn

b) tìm x để P<\(-\frac{1}{3}\)

c) tìm GTNN của P

c/m

\(\frac{1}{\sqrt{2}}+\frac{1}{\sqrt{3}}+...+\frac{1}{\sqrt{225}}< 28\)

cho bt với x≥0 , x≠9

P=\(\left(\frac{2\sqrt{2}}{\sqrt{x}+3}+\frac{\sqrt{x}}{\sqrt{x}-3}-\frac{3x+3}{x-9}\right):\left(\frac{2\sqrt{x}-2}{\sqrt{x}-3}-1\right)\)

a) rút gọn

b)tìm x để P<\(-\frac{1}{3}\)

c)tìm GTNN của P

CMR : \(\frac{1}{2}+\frac{1}{3\sqrt{2}}+\frac{1}{4\sqrt{3}}+...+\frac{1}{2020\sqrt{2019}}< 2\)

viết lại những câu sau sao cho nghĩa không thay đổi :

1.i'm sorry you don't study hard

2. i can't lend you any money

3. what a pity he doesn't invite us to the party

4. i'm sorry i can't easily give the answer

5. tom isn't here now

6. we don't buy that house

7. they never visit us

8. she is often for school