(11m - 6n)² = 121m² - 132 mn + 36n²
25 m^10 - 10m^4n^2 +n^4 = (5m^4 - n^2)²
5m-3n=5(-2/5)-3•2/3=-2-2=-4
(sinα+sin2α)/(1+cosα+cos2α)=tgα
1. sinα+sin2α=sinα+2sinαcosα=sinα*(1+2cosα)
2. 1+cosα+cos2α=1+cosα+2cos²α-1=cosα+2cos²α=cosα*(1+2cosα)
3. sinα*(1+2cosα)/(cosα*(1+2cosα))=sinα/cosα=tgα
4. tgα=tgα
B=log(75)81=log(5)81/log(5)75=4log(5)3/(2+log(5)3)
log(5)3=2b/(4-b)
a=log(5)3
a=2b/(4-b)
B6-b4=72 b5-b3=36 s5?
b1*q⁵-b1*q³=72
b1*q⁴-b1*q²=36
b1*q³(q²-1)=2b1*q²(q²-1) учтено 2*36=72
q³=2q² q=2 b1(q⁴-q²)=b1*12=36 b1=3
s5=b1(q⁵-1)/(q-1) = 3*31/1=3*31=93