A1q+a1q²+a1q³+a1q^4=180⇒a1[(1+q)+q²(1+q)]=180⇒a1(1+q)(1+q²)=180⇒
a1=180/(1+q)(1+q²)
a3-a1=36⇒a1q²-a1=36⇒a1(q²-1)=36⇒a1=36/(q+1)(q-1)
180/(1+q)(1+q²)=36/(1+q)(q-1)⇒
5/(1+q²)=1/(q-1)
1+q²=5q-5
q²-5q+6=0
q1+q2=5 U q1*q2=6
1)q1=2⇒a1=36/3=12
12;24;48;96
2)q2=3⇒a1=36/8=4,5
4,5;13.5;40,5;121,5