Question 19If $a$ and $b$ are positive, what is $\sqrt{a^2+\frac1{b^2}}\times\sqrt{b^2+\frac1{a^2}}$ equal to?$\frac ab+\frac ba$$a^2b^2+\frac1{a^2b^2}$$ab+2+\frac1{ab}$$a+b+\frac1a+\frac1b$$ab+\frac1{ab}$