# What is the standard form of a polynomial 7x(3-x+6x^3)?

Multiply each term in parenthesis by $\textcolor{red}{7 x}$ and then arrange the resulting terms in descending exponent size:
$\left(\textcolor{red}{7 x} \times 3\right) - \left(\textcolor{red}{7 x} \times x\right) + \left(\textcolor{red}{7 x} \times 6 {x}^{3}\right) \to$
$21 x - 7 {x}^{2} + 42 {x}^{4} \to$
$42 {x}^{4} - 7 {x}^{2} + 21 x$