If a-b=10 and ab=-21, then what is the value of a³-b³?

If $$64^{x+1}={64\over 4^x}$$, then the value of x

Solve the following equation.

If $${x}^2+{y}^2x+1=0$$ then the value of $$x^{31}+y{35}$$ is

If x²+y²+z² = xy + yz + zx, then the value of $${3x^4+7y^4+5z^4}\over{5x^2y^2+7y^2z^2+3z^2x^2} $$ is

If   $$ {{x+1}\over4x}={5\over 2}$$ then what is the value of   $$ 64x^6+1\over 8x^3  $$

If x = 2 then the value of $$ x^3 + 27x^2 + 243x + 631$$ is:

If a+b = 1 and a³+b³+3ab=k, then the value of k is :