1) (х+у)^2+(х-у)<span>^2=х<span>^2+2ху+у^2+х^2-2ху+у^2=2х^2+2у^2=2(х^2+у^2)</span></span>
3a-(6a-(2a-1))=3a-(6a-2a+1)=3a-6a+2a-1=-a-1
а)2a+3bc-1-a+3bc+1=2a+3bc-a+3bc=a+6bc
б)2a^9-10a^7+9a^7=2a^9-a^7=a^7*(2a^2-1)
в)5ab-3ac=a*(5b-3c)
г)2a^2b+12ab=2ab*(a+6b)
д)8a^3+4a^2=4a^2*(2a+1)