Помогите с 3 номера до 6 пожалуйста

3. (2a–3b)3b+(a–3b)^2= =6ab–9b^2+a^2–6ab+9b^2=a^2= =(-2/7)^2=4/49 4. a) 5(2–3xy)(2+3xy)=5(4–9x^2y^2)= =20–45x^2y^2 б) (a^3–b^2)^2=a^6–2a^3b^2+b^4 в) (х+у)^2–(х–у)^2=(х+у–х+у)(х+у+х–у)=4ху 5. (6а–1)(6а+1)–4а(9а+2)=–1 36а^2–1–36а^2–8а=–1 –8а=0 а=0 6. (2х+3)(3х–7)–(х+1)(х–1)=6х^2–14х+ +9х–21–х^2+1=(5х^2–5х–20)/5= =х^2–х–4 Ответ: да делится