a(a+b)(2a+1)= 2a³+a²+2a²b+ab
(a+1)*b*(b+2)= ab²+2ab+b²+2b
(a+1)(a+3)(2+3a)=(2+3a) (a²+4a+3)= 2a²+8a+6+3a³+12a²+9a=
= 3a³+14a²+17a+6
(2a+1)(2a+3)(2a+5)=(2a+5)(4a²+8a+3)=8a³+16a²+6a+20a²+40a+15=
=8a³+36a²+46a+15
(a+5)(a+2)+(1+a)= (a²+7a+10)(1+a)=a²+7a+10+a³+7a²+10a=
=a³+8a²+17a+10
