.............................
9ˣ - 2* 3⁽ˣ⁺²) + 45 = 0
3²ˣ - 2*3ˣ *3² + 45 = 0
3²ˣ - 18*3ˣ + 45 = 0
3ˣ = t
t² - 18t +45 = 0
по т.Виета t₁ = 15, t₂ = 3
1) t=15 2)t = 3
3ˣ = 15 3ˣ = 3
xlg3 = lg15 x = 1
x = lg15/lg3
3*2,5*10^(2-5)=7,5*10^(-3)=0,0075;
1.(9a^2-1)*(9a^2+1)=(3a-1)*(3a+1)*(9a^2+1)