Rút Gọn 

a)  A \(=\)\(\frac{1}{\sqrt{x}+\sqrt{x-1}}\)\(-\)\(\frac{1}{\sqrt{x}-\sqrt{x-1}}\)\(-\)\(\frac{x\sqrt{x}-x}{1-\sqrt{x}}\)( Rút gọn và Tìm x để A > 0 )

b) B \(=\)\(\left(2-\frac{a-3\sqrt{a}}{\sqrt{a}-3}\right)\)\(\left(2-\frac{5\sqrt{a}-\sqrt{ab}}{\sqrt{b}-5}\right)\)

c) C \(=\)\(\left(\frac{x-\sqrt{x}}{\sqrt{x}-1}+2\right)\)\(\left(2-\frac{\sqrt{x}+x}{1+\sqrt{x}}\right)\)

RÚT GON:

\(1.\)\(\frac{x\sqrt{x}-3}{x-2\sqrt{x}-3}-\frac{2\left(\sqrt{x}-3\right)}{\sqrt{x}+1}+\frac{\sqrt{x}+3}{3-\sqrt{x}}\)

\(2.\)\(\frac{\left(x+\sqrt{x}+1\right)^2+1}{\left(x+1\right)^2}-\frac{\left(x-\sqrt{x}-1\right)^2-1}{\left(1-x\right)^2}\)

\(3.\)\(\frac{3x+\sqrt{9x}-3}{3+\sqrt{x}-2}-\frac{\sqrt{x}+1}{\sqrt{x}+2}+\frac{\sqrt{x}-2}{1-\sqrt{x}}\)

Cho \(A=\left(\frac{1}{\sqrt{x}-1}-\frac{1}{\sqrt{x}+1}\right)\left(\frac{x+4}{2}-\sqrt{x}\right)\)

1. Tìm \(ĐKXĐ\)

2. Rút gọn \(A\)

3. Tìm \(x\)để \(A=\frac{\sqrt{x}}{6}\)

4. Tìm \(x\)thuộc\(Z\)để \(A\)thuộc\(Z\)

5. Tính giá trị của \(A\)khi \(x=7-2\sqrt{2}\)

6. Tìm \(x\)để \(A\)> (h) = \(\frac{1}{3}\)

Bài 1 : Cho bt M = \(\left(\frac{\sqrt{x}}{x-4}\right)+\left(\frac{1}{\sqrt{x}-2}\right).\frac{\sqrt{x}-2}{2}\)

a) tim dkxd va RG A .

b) tim \(x\in Z\)de \(2M\in Z\)

Bài 2 : cho bt A = \(\left(\frac{\sqrt{x}+1}{x-2\sqrt{x}}-\frac{1}{\sqrt{x}-2}\right).\left(x-3\sqrt{x}+2\right)\)

a) tìm ĐKXĐ và RG A

b) tìm x để \(A< \frac{1}{2}\)

c) tim \(x\in Z\)de \(A\in Z\)

chứng minh

a. \(\frac{x\sqrt{x}+y\sqrt{y}}{\sqrt{x}+\sqrt{y}}-\left(\sqrt{x}-\sqrt{y}\right)^2=\sqrt{xy}\)

b. \(\frac{\sqrt{x+2\sqrt{x-2}-1}.\left(\sqrt{x-2}-1\right)}{\sqrt{x}-3}=\sqrt{x}+\sqrt{3}\) Với x \(\ge\)2; x \(\ne\)3

c.\(\left(\frac{1}{a-\sqrt{a}}+\frac{1}{\sqrt{a}-1}\right):\frac{\sqrt{a}+1}{a-2\sqrt{a}+1}=\frac{\sqrt{a}-1}{\sqrt{a}}\) Với a > 0; a \(\ne\)1

d.\(\sqrt{\frac{x-6\sqrt{x}+9}{x+6\sqrt{x}+9}}\) Với x \(\ge\) 0

e. \(\left(x-y\right).\sqrt{\frac{xy}{\left(x-y\right)^2}}\)

1, A=\(\left(\frac{\sqrt{x}+2}{x+2\sqrt{x}+1}-\frac{2}{\sqrt{x}+1}\right):\frac{x-1}{\sqrt{x}}\) với x > 0

a, Rút gọn

b, Tìm x nguyên nhỏ nhất để A < 0

c, Tìm \(x\in Z\) để \(A\in Z\)

2, Rút gọn: \(\left(\frac{14}{\sqrt{14}}+\frac{\sqrt{12}+\sqrt{30}}{\sqrt{5}+\sqrt{2}}\right).\sqrt{5-\sqrt{21}}\)

3, Cho \(\left|x\right|< 1,\left|y\right|< 1\). Chứng minh \(\frac{1}{1-x^2}+\frac{1}{1-y^2}\ge\frac{2}{1-xy}\)

Bạn nào giúp mk thứ 2 phải nộp rồi!!!

Giải giúp mik vs đap cần gấp . Cảm ơn mn. Giải cho mik bài 1 cx đc

1/ Rút gọn

A=\(\sqrt{7}-4\sqrt{3}+\sqrt{4}-2\sqrt{3}\)

B=\(\left(2+\frac{5-\sqrt{5}}{\sqrt{5}-1}\right)\) \(\left(2-\frac{5+\sqrt{5}}{\sqrt{5}+1}\right)\)

C=\(\left(\sqrt{3}+1\right)\) \(\left(\frac{\sqrt{14}-6\sqrt{3}}{5+\sqrt{3}}\right)\)

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

a/ cmr: P>0, V x >0, x\(\ne\)1

b/Tính GT P khi x\(\frac{2}{2+\sqrt{3}}\)

\(B=\left(\frac{x\sqrt{x}+x+\sqrt{x}}{x\sqrt{x}-1}-\frac{\sqrt{x}+3}{1-\sqrt{x}}\right).\frac{x-1}{2x+\sqrt{x}-1}\)  ĐKXĐ: ...

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

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

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

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

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

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

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

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

\(=\frac{2\sqrt{x}+3}{2\sqrt{x}-1}\)