(b+8)(b-3)=b²-3b+8b-24=b²+5b-24
(6p-q) (3p+5q) =18p²+30pq-3pq-5q²=
18p²+27pq-5q²
(a+4)(a²-6a+2)=a³-6a²+2a+4a²-24a+8=
=a³-2a²-22a+8
a(x+y) -5(x+y) =(x+y)(a-5)
5a-5b+da-db=(5a-5b)+(da-db) =
=5(a-b)+d(a-b) =(a-b)(5+d)
m(m-n)-(m²-n²)(2m+n)=
m(m-n)-(m-n)(m+n)(2m+n) =(m-n)m(m+n)(2m+n)
b(b-3)-18=(b+3)(b-6)
b(b-3)-18=b²-3b-18
(b+3)(b-6)=b²-6b+3b-18=b²-3b-18