I1.1 Find $a$ if $a=5+8+11+\ldots+38$.
I1.2 Let $b=$ the sum of the digits of the number $a$. Find $b$.
I1.3 If $c=b^{2}$, find $c$.
I1.4 Given that $3 d=c$, find $d$.
This is an arithmetic series with first term $=5$, common difference $=3$ Let $n$ be the number of terms. $38=5+(n-1)(3) \Rightarrow n=12$
$$
\begin{array}{l}
a=\frac{1}{2}(5+38) \cdot 12=258 \\
b=2+5+8=15 \\
c=15^{2}=225 \\
3 d=225 \Rightarrow d=75
\end{array}
$$

Put $x=-4$ into the polynomial: $2(-4)^{2}+3(-4)+4 d=0$
$$
d=-5
$$