If x²+4y²=17 and xy=2, where x>0,y>0, then what is the value of x³+8y³?

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

If a = 7, b = 5 and c = 3, then the value of $$a^2+b^2+c^2-ab-bc-ca$$ is 

if a=26 and b=22, then the value of   $${{a^3-b^3}\over {a^2-b^2}}-{3ab\over a+b}$$ is

If 4x² + y² = 40 and xy = 6, then find the value of 2x + y.

$$ {x^{8}+4\over{x^{4}+2x^{2}+2}}$$ is equal to

If x = a - b, y = b - c, z = c - a, then the numerical value of the algebraic expression x³ +y³ + z³ -3xyz will be 

If a=25, b=15 , c=-10 then find the value of $$ {a^{3}+b^{3}+c^{3}-3abc\over {(a-b)^{2}+(b-c)^{2} +(c-a)^{2}}}$$