If x²+y²-4x-4y+8=0, then the value of x-y is: 

If  $$\sqrt{a}+\sqrt{b}=15 \ and \ (\sqrt{a}-\sqrt{b} )=3$$ then the value of $$\sqrt{ab/4} $$ is 

If (a+b)=16 and a³+b³=1456, then what is the value of ab?

Find the value of. 67²–33².

If $$ {x=a^{2\over3}-a^{-2\over3}}$$ then the value of $$ {x^{3}+3x}$$.

If $$ P={{x^2-36}\over{x^2-49}}$$ and $$ Q={{x+6}\over{x+7}}$$ then the value of $$ {P\over{Q}}$$ is.

If 0.4 m + 0.8 n = 2.2 and 0.8 m + 0.4 n = 1.4, then the value of $$ {m^2}+{n^2}$$ is equal to 

If x, y are two positive real number and  $$x^{1/3}=y^{1/4}$$, then which of the following relations is true?