$$ { \sqrt{(0.798)^2+0.404×0.798+(0.202)^2}+1=?} $$

The largest number of five digits, which is a perfect square is 

Simplify : $$\sqrt{[(12.1)^2-(8.1)^2]÷[(0.25)^2+(0.25)(19.95)]} $$

The smallest natural number, by which 3000 must be divided to make the quotient a perfect cube, is : 

The value of $$ {\sqrt{0.6912}+{\sqrt{0.5292}}\over {\sqrt{0.6912}-{\sqrt{0.5292}}}}$$ is:

3x² = 36 then what is the value of x?

What mathematical operation should come at the place of ‘?’ in the equation:
2 ? 6 – 12 ÷ 4 +2 =11.

If $$ {3\sqrt{{1-a}\over{a}}}+9={19-3\sqrt{{a}\over{1-a}}}$$, then what is the value of a?