А) (0,8х+15)(0,8х–15)+0,36х^2 =
= 0,64х^2–225+0,36х^2=х^2–225=
= (х–15)(х+15)
б) (2a+b)(4a^2+b^2)(2a–b)=(4a^2–b^2)(4a^2+b^2)=16a^4–b^4
в) (с^3+b)(c^3–b)(c^6+b^2)=
= (c^6–b^2)(c^6+b^2)= c^12–b^4
г) (3а–1)(3а+1)–17а^2=9а^2–1–17а^2=
= –8а^2–1
д) 100х^2–(5х–4)(4+5х)=100х^2–25х^2+16=75х^2+16
е) 22с^2+(–3с–7)(3с–7)=22с^2–9с^2+49=13с^2+49