81c² - d² + 9c + d = (81c² - d²) + (9c + d) = (9c - d)(9c + d) + (9c + d) =
= (9c + d)(9c - d + 1)
Ответ: В прикрепленной ниже фотографии.
(3х+2)^2+(4х+1)(4х-1)=(5х-1)^2=9х^2+12х+4+16х^2-4х+4х-1=25х^2-10х+1
9х^2+12х+16х^2-4х+4х-25х^2+10х=-4+1+1
22х=-2
х=-2:22
х=-1\11