X-27-63=115 x-90=115 x=115+90 x=205
(2+5i)•(-3+4i)=-6-15і+8і+20і²=20і²-7і-6
N=1 b=1/9, n=2 b=1/3, n=3 b=1, n=4 b=3 ∑b4= 1/9+1/3+1+3=4 4/9
Log₁/₃(√3/(7+2*√10))+log√₃(1/(√5+√2))=
=log₃⁻¹(√3/(7+2*√10))+log₃¹/²(1/(√5+√2))=
=log₃(√3/(7+2*√10))⁻¹+log₃(1/(√5+√2)²)=
=log₃((7+2*√10)*1)/(√3*(√5+√2)²)=
=log₃(7+2√10)/(√3*((√5)²+2*√5*√2+(√2)²))=
=log₃(7+2√10)/(√3*(7+2*√10))=
=log₃(1/√3)=log₃3⁻¹/²=-1/2.