a) Substitute $x =  - 2$, equate to zero and obtain a correct equation in any form

Substitute $x =  - 1$ and equate to 12

Obtain a correct equation in any form

Solve a relevant pair of equations for $\alpha $ or $b$

Obtain $\alpha  = 2$ and $b = 6$

b) Attempt division by $x + 2$ and reach a partial quotient of $2{x^2} - 7x$

Obtain quotient $2{x^2} - 7x + 3$

Obtain linear factors $2x - 1$ and $x - 3$

[Condone omission of repetition that $x + 2$ is a factor.]

[If linear factors $2x - 1$, $x - 3$ obtained by remainder theorem or inspection, award B2 + B1.]

S.C. M1A1√ if $\alpha $, $b$ not both correct