а) (3х+9)(х-1) = 3х²-3х+9х-9 = 3х²+6х-9
б) (5х-1)(х+3) = 5х²+15х-х-3 = 5х²+14х-3
в) (2х+5)(4х-1) = 8х²-2х+20х-5 = 8х²+18х-5
г) (3-4х)(х+2) = 3х+6-4х²-8х = -4х²-5х+6
а) (3х+9)(х-1) = 3х²-3х+9х-9 = 3х²+6х-9
б) (5х-1)(х+3) = 5х²+15х-х-3 = 5х²+14х-3
в) (2х+5)(4х-1) = 8х²-2х+20х-5 = 8х²+18х-5
г) (3-4х)(х+2) = 3х+6-4х²-8х = -4х²-5х+6