A) 15^(2-log₁₅9)=15²*15^(-log₁₅9)=225/15^(log₁₅9)=225/9=25.
b) 2*log₁/₅5+log₁/₅5+0,5*log₁/₅25=log₁/₅5²+log₁/₅5+log₁/₅√25=
=log₁/₅25+log₁/₅5+log₁/₅5=log₁/₅(25*5*5)=-log₅625=-log₅5⁴=-4*log₅5=-4.
<span> (cosa//1-sina -cosa//1+sina)=2tga</span>
<span>5sinactga=5cosa
</span>
<span>5sina + 13sina*tga//-2cosa-2sina//cosa=9sina+13sinatga/(-2cosa)
</span>
6 2/3=20/3
100%................20/3
10%.................20/3 :10=20/30=2/3
30%................3.(2/3)=2
Otvet:2
<span>Пишите, если что не так</span>