b1+b2+b3=70
b1 * b2 * b3=8000
bn=b1 * q^(n-1)
b2=b1 * q
b3=b2 * q^2
b1+b1 * q+b2 * q^2=70
b1(1+q+q^2)=70
b1=70/(1+q+q^2)
b1 * b1 * q * b2 * q^2= 8000
b1^3 * q^3=8000
(70/(1+q+q^2))^3 * q^3=8000
70/(1+q+q^2) * q =20
70q=20(1+q+q^2)
70q-20-20q-20q^2=0
-20q^2+50q-20=0
2q^2-5q+2=0
D=25-4 * 2 * 2=9
q1=(5-3)/4=1/2
q2=(5+3)/4=2
b1(1)=70/(1+q+q^2)=70/(1+1/2+1/4)=40.
b1(2)=70/(1+2+4)=10
Ж: Еселігі 1/2 және 2-ге тең.
b1 10 н/е 40-тең.
