Ответ:\(a(b+c)+p(b+c)=(a+p)(b+c)\).\(2a+b+2a^2+ab=(2a+b)+a(2a+b)=(a+1)(2a+b)\).\(a^2-9y^2=a^2-(3y)^2=(a-3y)(a+3y)\).\(100c^2-25b^2=(10c)^2-(5b)^2=(10c-5b)(10c+5b)=25(2c-b)(2c+b)\).