Every general cubic equation $a w^{3}+b w^{2}+c w$ $+d=0$ can be written in the form $x^{3}+p x+$ $q=0$ (where the squared term has been "depressed"), using the transformation $w=x-\frac{b}{3} .$ Use this transformation to solve the following equations.
a. $w^{3}-3 w^{2}+6 w-4=0$
b. $w^{3}-6 w^{2}+21 w-26=0$
Note: It is actually very rare that the transformation produces a value of $q=0$ for the "depressed" cubic $x^{3}+p x+q=0,$ and general solutions must be found using what has become known as Cardano's formula. For a complete treatment of cubic equations and their solutions, visit our website at www.mhhe.com/coburn. Here we'll focus on the primary root of selected cubics.