If $$ {x^4}+{1\over{x^4}}$$ then find $$ {x^3}-{1\over{x^3}}=?$$

If 5^√x + 12^√x = 13^√x, then x is equal to: 

If $$ {x+{1\over x}}=2$$ then find out the value of $${2x^2+2}\over{3x^2+5x+3}$$

$$ {a^2-b^2-2bc-c^2}\over{a^2+b^2+2ab-c^2}$$ is equal to

If xy(x+y)=1, then $$ {1\over x^3 y^3}-{x^3-y^3}$$ is equal to-

If (27x³ – 343y³) ÷ (3x – 7y) = Ax² +By² + 7Cyx, then the value of (4A – B +5C) is:

If $$x=(\sqrt2+1)^{1\over3} $$, the value of $$(x^3-{1\over {x^3}}) $$ is

if $$x-{1\over 5},x≠0,$$ then what is the value of $${x^6+3x^3-1}\over x^6-8x^3-1$$=?