3.А).2*4-3=5
4.(625·81·15)¹/³)/225)¹/³=((125·5·3·27·15)/225)/¹³=(225·125·27)/225)¹/³=
=(5³· 3³)¹/³=5·3=15
5.sinα=√(1-сos²α)=√(1-0,36)=√0,64=0,8
6.2⁷ˣ⁻⁵=(1/8)²ˣ⁺¹=(2⁻³)²ˣ⁻¹,
2⁷ˣ⁻⁵=2⁶ˣ⁺³,7x-5=6x+3,x=5+3,x=8
7.Log₆(2/3)+Log₆3²+2=Log₆(2/3·9)+2=Log₆6+2=1+2=3
8.Lg(2x+1)=0, 2x+1=10⁰,2x+1=1,2x=0,x=0