If $(2x + 3)(3x - 1) = 6x^2 + kx - 3$,then find the value of $k$.

Expand: $(x+3y-5z)^{2}$

Which of the following expressions are polynomials in one variable and which are not? State reason for your answer. If the given expression is a polynomial,state whether it is a polynomial in one variable or not: $x^{2}-8x+15$

Write the coefficient of $x^{2}$ in each of the following:
$(i)$ $\frac{\pi}{6} x + x^{2} - 1$
$(ii)$ $3x - 5$

Classify the following as a constant,linear,quadratic,or cubic polynomial:
$3x^3$

Factorise the following quadratic polynomial by splitting the middle term:
$x^{2}+14x+33$