$1\mathrm{.}2$: Suppose you are given integers a$,$ b$,$ c$,$ and d$,$ and you must compute

the two quantities

x $=$ ab$-$cc$+$bd

and

y $=$ bb$-$cc$+$ad$.$

As written, the equations suggest doing six multiplications, though clearly

if cc is computed and stored in an intermediate variable, then only five

multiplications are needed. This could be expressed algorithmically as:

temp$1=$ c$*$c

x $=$ a$*$b $-$ temp$1+$ b$*$d

y $=$ b$*$b $-$ temp$1+$ a$*$d

which clearly illustrates how to compute the result with five multiplications.

That still is not very efficient, though.