## Elementary Technical Mathematics

$$4a^3-3a^2-5a.$$
We simplify by adding the $a^3$-terms as follows $$3a^3+a^3=4a^3,$$ adding the $a^2$-terms, $$2a^2-5a^2=-3a^2$$ adding the $a$-terms, $$-7a+4a-2a=-5a$$ adding the constant terms, $$5-2-3=0$$ The result is $$4a^3-3a^2-5a.$$