If $${\sqrt{7-2}\over\sqrt{7+2}}=a\sqrt{7}+b$$, then the value of a is : 

If  $$ \ {xy\over x+y}= a, $$ $${xz\over x+z}=b $$ and $$ {yz\over y+z} =c $$  where a, b, c are all non – zero numbers, then x equals to

If $$ \sqrt {x^2+y^2}=25$$, and y=2x, find x. 

Simplification 

If then the value of

If average of two x and $$1\over x$$ (where x ≠ 0) is A, what will be the average of x³ and $$1\over {x^3}$$?

If $$ x={\sqrt3\over{2}}$$ then the value of $$ \sqrt{1+x}-\sqrt{1-x}$$ will be

If a = 2.234, b = 3.121 and c = –5.355, then the value of $$ a^3 + b^3 + c^3 – 3abc$$ is