Question

\(\dfrac{a+b-2\sqrt{ab}}{\sqrt{a}-\sqrt{b}}-\dfrac{a-b}{\sqrt{a}+\sqrt{b}}\)

rút gọn

 

Answer 1

`= (sqrt a - sqrt b)^2/(sqrt a - sqrt b) - ((sqrt a - sqrt b)(sqrt a + sqrtb))/(sqrt a + sqrt b)`

`= sqrt a - sqrt b - sqrt a + sqrt b`

`= 0`

Answer 2

đk a> 0 ; b>0

\(=\dfrac{\left(\sqrt{a}-\sqrt{b}\right)^2}{\sqrt{a}-\sqrt{b}}-\dfrac{\left(\sqrt{a}+\sqrt{b}\right)\left(\sqrt{a}-\sqrt{b}\right)}{\sqrt{a}+\sqrt{b}}\\ =\sqrt{a}-\sqrt{b}-\left(\sqrt{a}-\sqrt{b}\right)\\ =\sqrt{a}-\sqrt{b}+\sqrt{a}+\sqrt{b}\\ =2\sqrt{a}\)