9
(3a³-b³)/(3a-b(a+4b))=(81+8)/(9+2(3-8))=89/(9-10)=-89
10
(zt+3t²²-z²²)/(z³³+2z²²+zt-t²²)=(-3/4*1/2+3*1/4-9/16)/(-27/64+18/16-3/8-1/4)=
=(-6/16+12/16-9*16)/(-27/64+72/64-24/64-16/64)=-3/16:5/64=
=-3/16*64/5=-12/5=-2,4
11
√(x+y²=√(0,4+0,09)=√0,49=0,7