по заданному составьте геометрическую прогрессию - система: а2-a1=-4 и a3-a1=8 2)система :а1+а4=0,4375 и а3-а2+а1=0,875

1{a2-a1=-4⇒a1q-a1=-4⇒a1(q-1)=-4⇒a1=-4/(q-1){a3-a1=8⇒a1q²-a1=8⇒a1=8/(q²-1)-4/(a-1)=8/(q-1)(q+1)-1=2/(q+1),q≠1q+1=-2q=-3a1=-4/(-3-1)=-4/(-4)=1an=1*(-3)^n-1=(-3)^n-12{a1+a4=0,4375⇒a1+a1q³=0,4375⇒a1(1+q³)=0,4375⇒a1=0,4375/(1+q³){a3-a2+a1=0,875⇒a1q²-a1q+a1=0,875⇒a1(q²-q+1)=0,875⇒a1=0,875/(q²-q+1)0,4375/(1+q³)=0,875/(q²-q+1)1/(1+q³)=2/(q²-q+1)1/(q+1)(q²-q+1)=2/(q²-q+1)1/(q+1)=2q+1=0,5q=-0,5a1=0,4375/(1-0,125)=0,4375/0,875=0,5an=0,5*(-0,5)^n-1