Question

help me 

Answer 1

a.

\(B=\dfrac{\sqrt{a}\left(\sqrt{a}+3\right)}{\left(\sqrt{a}-3\right)\left(\sqrt{a}+3\right)}-\dfrac{3\left(\sqrt{a}-3\right)}{\left(\sqrt{a}-3\right)\left(\sqrt{a}+3\right)}-\dfrac{a-2}{\left(\sqrt{a}-3\right)\left(\sqrt{a}+3\right)}\)

\(=\dfrac{\sqrt{a}\left(\sqrt{a}+3\right)-3\left(\sqrt{a}-3\right)-\left(a-2\right)}{\left(\sqrt{a}-3\right)\left(\sqrt{a}+3\right)}\)

\(=\dfrac{11}{\left(\sqrt{a}-3\right)\left(\sqrt{a}+3\right)}=\dfrac{11}{a-9}\)

b.

B nguyên khi \(\dfrac{11}{a-9}\) nguyên

\(\Rightarrow a-9=Ư\left(11\right)\)

\(\Rightarrow a-9=\left\{-11;-1;1;11\right\}\)

\(\Rightarrow a=\left\{-2;1;10;20\right\}\)