Sin²3x+sinx+cos²3x=0
(sin²3x+cos²3x)+sinx=0
1+sinx=0
sinx=-1
x=3π/2+2πn, n∈Z
f(2) = 4/2 = 2
f(a) = 4/a
f ((a-1) + 1) = 4 / (a-1)+1
-3x+1+x-5=15-5x+5
3x=24
x=8
<span>b3,если q=0.1 и S=10
S=b1/(1-q) => b1=S*(1-q)
b3</span>=b1*q^2=<span>S*(1-q)*</span>q^2 = 10*(1-0,1)*0,1^2 = <span>
0,09
</span>
*****************
b5,если q=0.2 и S=5;
аналогично
<span>b1=S*(1-q)
b5=</span>b1*q^4=S*(1-q)*q^4 = 5*(1-0,2)*0,2^4 = <span>
0,0064
</span>
8х-5,6=0
8х=5.6
х=5,6\8
х=0.7