$\left(x+1\right)$ is a factor of the polynomial

One of the factors of $\left(25x^2-1\right)+(1+5x{)}^2$ is

The factorisation of $4x^2+8x+3$ is

The coefficient of $x$ in the expansion of $(x+3{)}^3$ is

If $\frac{x}{y}+\frac{y}{x}=-1 (x,y\ne 0)$, the value of $x^3-y^3$ is

If $49x^2-b=\left(7x+\frac{1}{2}\right)\left(7x-\frac{1}{2}\right)$, then the value of $b$ is

If $a + b + c = 0$, then the value of $a^3 + b^3 + c^3$ is equal to