If $|x| < 1$,then the coefficient of $x^n$ in the expansion of $(1 + x + x^2 + ....)^2$ will be

To expand $(1 + 2x)^{-1/2}$ as an infinite series,the range of $x$ should be

If $n$ is a positive integer and the coefficient of $x^{10}$ in the expansion of $(1+x)^{15}$ is equal to the coefficient of $x^5$ in the expansion of $(1-x)^{-n}$,then $n=$

If $x = \frac{2 \cdot 5}{2! \cdot 3} + \frac{2 \cdot 5 \cdot 7}{3! \cdot 3^2} + \frac{2 \cdot 5 \cdot 7 \cdot 9}{4! \cdot 3^3} + \ldots$,then $x^2 + 8x + 8 = $

If the value of $x$ is so small that $x^2$ and higher powers can be neglected,then $\frac{\sqrt{1 + x} + \sqrt[3]{(1 - x)^2}}{1 + x + \sqrt{1 + x}}$ is equal to

If $(a+bx)^{-3} = \frac{1}{27} + \frac{1}{3}x + \dots$,then the ordered pair $(a, b)$ is equal to