решение уравнения 4(х+1)=15х-7(2х+5)4х+4=15х-14х-354х-15х+14х=-35-43х=-39х=-39:3х=-13а)3х^2+9ху=3х(х+3у)12аb-5a-ab+6a=(12ab-ab)-(5a+6a)=11ab-11a=11a(b-1)2х/3+2х+1/6=3х-5/42х/3-2х+3х=-5/4-1/62х/3-6х/3-9х/3=-30/24-4/24-13/3х=-34/24х=-34/24:-(13/3)х=-34/24*(-3/13)х=34/104=17/52=0,334x(а+х+у)+4a(а-х-у)-4y(х-а-у)=4ха+4х^2+4ху+4а^2-4ах-4ау-4ух+4уа+4у^2=4х^2+4a^2+4y^2=4(x^2+a^2+y^2)