cho 2 bieu thuc:

A=(\(\sqrt{20}\) -\(\sqrt{45}\) +3\(\sqrt{5}\) ).\(\sqrt{5}\)  va B=\(\dfrac{x+1-2\sqrt{x}}{\sqrt{x}-1}\) +\(\dfrac{x+\sqrt{x}}{\sqrt{x}+1}\) (Dieu kien: x>0, x  khac 1

a) Rut gon bieu thuc A va B

b)Tim cac gia tri cua x de gia tri cua bieu thuc A bang 2lan gia tri B

rút gọn biểu thức:

a, \(\sqrt{\left(2,5-0,7\right)^2}\)

b, \(\dfrac{\sqrt{3^2}+\sqrt{39^2}}{\sqrt{7^2}+\sqrt{91^2}}1\)

(\(\dfrac{1}{\sqrt{x}-\sqrt{x-1}}-\dfrac{x-3}{\sqrt{x-1}-\sqrt{2}})\left(\dfrac{2}{2-\sqrt{x}}-\dfrac{\sqrt{x}+\sqrt{2}}{2\sqrt{x}-x}\right)\)
Rut gon bieu thuc

1) Rut gon bieu thuc A = \(\left(4+\sqrt{7}\right).\left(\sqrt{2}-\sqrt{14}\right).\sqrt{4-\sqrt{7}}\)

rut gon bieu thuc

A=\(\left(\dfrac{\sqrt{X}+2}{X-9}-\dfrac{\sqrt{X}-2}{X+6\sqrt{X}+9}\right)\left(\sqrt{X}\dfrac{9}{\sqrt{X}}\right)\)

Cho bieu thuc:        \(p=\left(\frac{1}{\sqrt{x}-\sqrt{x-1}}-\frac{x-3}{\sqrt{x-1}-\sqrt{2}}\right)\left(\frac{2}{\sqrt{2}-\sqrt{x}}-\frac{\sqrt{x}+\sqrt{2}}{\sqrt{2x}-x}\right)\)

a) Tim DKXD cua bieu thuc p

b) Rut gon bieu thuc p

rut gon bieu thuc: \(\frac{\sqrt{\sqrt{\frac{x-1}{x+1}}+\sqrt{\frac{x+1}{x-1}}-2}\left(2x+\sqrt{x^2+1}\right)}{\sqrt{\left(x+1\right)^3}-\sqrt{\left(x-1\right)^2}}\)

\(\left(3+\frac{a-2\sqrt{a}}{\sqrt{a}-2}\right)\left(3-\frac{3a+\sqrt{a}}{3\sqrt{a}+1}\right).Rut\:gon\:bieu\:thuc\:nay\)

a,\(\dfrac{5^4.20^4}{25^5.4^5}\) b,\(\dfrac{\left(5^4-5^3\right)^3}{125^4}\) c,\(\sqrt{\left(2,5-0,7\right)^2}\) d,\(\dfrac{\sqrt{3^2+\sqrt{39^2}}}{\sqrt{7^2+\sqrt{91^2}}}1\)

Ai biết rút gọn biểu thức này k ạ??
Giups mình với!!! Cảm ơn nhiều ạ!!