If a + b – c = 0 then the value of 2b²c² + 2c²a² + 2a²b² –a⁴ – b⁴ – c⁴

If   $$ a={b^2\over b-a} $$  then the value of a³ + b³ is 

Find the radius of the circle x²+y²-4x+6y=12

If x = 2 then the value of x³ + 27x² + 243x + 631 is

If   $$x+{1\over x}=2 $$ then the value of    $$x^{12}-{1\over x^{12}} $$ is

if $$a+{1\over a}=5$$, then what is the value of $$a^3+{1\over a^3}$$

The HCF of x⁸ – 1 and x⁴ + 2x³ – 2x – 1 is :

If 27(x+y)³ – 8(x-y)³=(x+5y)(Ax²+By²+Cxy), then what is the value of (A+B-C)?