Question

Nếu , với , thì  ....

Answer 1

\(\sqrt{10-2\sqrt{21}}=\sqrt{\left(\sqrt{7}-\sqrt{3}\right)^2}\)

=\(\sqrt{7}-\sqrt{3}\)

=> a=7 và b=3

=> a-b=7-3=4

Answer 2

\(\sqrt{10-2\sqrt{21}}=\sqrt{7}-\sqrt{3}\)

\(\Rightarrow\sqrt{7}-\sqrt{3}=\sqrt{a}-\sqrt{b}\)

Suy ra \(\sqrt{7}=\sqrt{a}\rightarrow a=7\)

\(\sqrt{3}=\sqrt{3}\rightarrow b=3\)

Vậy \(a-b=7-3=4\)