If $x+2$ is a factor of $x^{3}+ax^{2}-x+30$,find the value of $a$.

Expand $(2a + 3b)(2a - 5b)$.

Expand $(3x + 7)(-3x + 7)$.

Using a suitable identity,evaluate the following:
$101 \times 102$

With the help of the remainder theorem,find the remainder when the polynomial $p(x) = x^{3} + x^{2} - 26x + 24$ is divided by the divisor $x - 4$.

Which of the following expressions is a polynomial? State the reason. If an expression is a polynomial,state whether it is a polynomial in one variable or not.
$5x^2 + 11x - 2\sqrt{x}$