11(х+у)-х(х+у) =
= (х+у)(11-х)
b2=b1*q=9
b4=b1*q^3=b1*q*q^2=b2*q^2=9*q^2=16
q^2=16/9
b6=b1*q^5=b1*q^3*q^2=b4*q^2=16*q^2=16*16/9
ответ:256/9