Найдите q, bn, Sn геометрической прогрессии, если : 1) b1=0,7 ; b3=2,8 ; n=6 2) b1=0,6 ; b2=1,8 ; n=5 3) b1= -0,2 ; b2=1,4 ; n=4
Объяснение:
1)
Ответ: a) q=2, b₆=22,4, S₆=44,1.
b) q=-2, b₆=-22,4, S₆=-14,7.
2)
Ответ: q=3, b₅=48,6, S₅=72,6.
3)
Ответ: q=-7, b₄=68,6, S₄=60.
%5C%20q_1%3D2%5C%5Cb_6%3Db_1q%5E5%3D0%2C7*2%5E5%3D0%2C7*32%3D22%2C4.%5C%5CS_6%3D0%2C7*%5Cfrac%7B2%5E6-1%7D%7B2-1%7D%3D%200%2C7*%5Cfrac%7B64-1%7D%7B1%7D%20%3D0%2C7*63%3D44%2C1.%5C%5Cb)%5C%20q%3D-2%5C%5Cb_6%3D0%2C7*(-2)%5E5%3D0%2C7*-32%3D-22%2C4.%5C%5CS_6%3D0%2C7*%5Cfrac%7B(-2)%5E6-1%7D%7B-2-1%7D%20%3D0%2C7*%5Cfrac%7B64-1%7D%7B-3%7D%20%3D0%2C7*%5Cfrac%7B63%7D%7B-3%7D%20%3D-0%2C7*21%3D-14%2C7.)
2%3D1%2C4%5C%20%5C%20%5C%20%5C%20n%3D4%20q%3D%3F%5C%20b_n%3D%3F%5C%20Sn%3D%3F%5C%5Cq%3D%5Cfrac%7B1%2C4%7D%7B-0%2C2%7D%3D-7.%5C%5C%20b_4%3D-0%2C2*(-7)%5E3%3D-0%2C2*(-343)%3D68%2C6.%5C%5CS_4%3D-0%2C2*%5Cfrac%7B(-7)%5E4-1%7D%7B-7-1%7D%20%3D-0%2C2*%5Cfrac%7B2401-1%7D%7B-8%7D%20%3D0%2C2*%5Cfrac%7B2400%7D%7B8%7D%20%3D0%2C2*300%3D60.)