In the expansion of (1 + ax)ⁿ, the first three terms are respectively 1, 12x and 64x². What is n equal to?

 If $x=(1111){}^2$, $y=(1001){}^2$ and $z=(110){}^2$, then what is x³−y³−z³−3xyz equal to?

What is the number of rational terms in the expansion of $(\sqrt{3}+5^\frac{1}{4})^{12}$

If the sum of binomial coefficients in the expansion of $(x+y){}^n$ is 256, then the greatest binomial coefficient occurs in which one of the following terms?