Геом прогрессия: b1-b2=28 b4-b3=-252 найти b1 b2 b3 b4

{b1-b2=28⇒b1-b1q=28⇒b1 (1-q) = 28⇒b1=28 / (1-q)

{b4-b3=-252⇒b1q³-b1q²=-252⇒b1q² (q-1) = - 252⇒b1=252/q² (1-q)

28 / (1-q) = 252/q² (1-q)

1=9/q²

q²=9

q1=-3⇒b1=28 / (1+3) = 7, b2=7 * (-3) = - 21, b3=-21 * (-3) = 63, b4=63 * (-3) = - 189

q2=3⇒b1=28 / (1-3) = - 14, b2=-14*3=-42, b2=-42*3=-126, b3=-126*3=-378, b4=-378*3=1134