5. If 64 and 27 are the first and the fourth terms of a geometric series respectively, find the sum to infinity of the geometric seires.
6. A rubber ball is dropped vertically from a height of 40 cm . Every time it reaches the ground , it rerbounds to a height which is 3/5 of its prevoius height. What is the total distance the ball has traveled up and down
(a) just before the 2 ^nd rebound
(b) just before the 3^rd rebound
(c) before coming to rest
above those questions need to clear step and need to 翻譯 chinese, thank you so much ar^^
math hw meet difficulty , have anyone can help me
2008-11-25 7:16 am
回答 (2)
2008-11-26 2:54 am
5.如果64 和27 分別是第1 和幾何學系列的第4 個條件，對幾何學seires的無限找到總數。
6.一個橡膠球被從40厘米的高度垂直放下。 每當它對是它的prevoius 高度的3/5的高度到達rerbounds 地，它。 什麼是球已經上下旅行的總距離
(a)在這2個前一會兒 ^ nd 彈回
(b)在這3個前一會兒 ^ rd 彈回
(c)在甦醒休息之前
6.一個橡膠球被從40厘米的高度垂直放下。 每當它對是它的prevoius 高度的3/5的高度到達rerbounds 地，它。 什麼是球已經上下旅行的總距離
(a)在這2個前一會兒 ^ nd 彈回
(b)在這3個前一會兒 ^ rd 彈回
(c)在甦醒休息之前
2008-11-25 7:45 am
Question 5
27 = 64 x (R ^ 3)
R = 0.75
so,
64 x [1 + R + (R ^ 2) + (R ^ 3) + ... ... + (R ^ n) + ... ...]
= 64 / (1 - R) = 256
Question 6
a)
40cm + 2 x (3 / 5) x 40cm = 88cm
b)
88cm + 2 x [(3 / 5) ^ 2] x 40cm = 116.8cm
c)
40cm x {1 + 2 x (3 / 5) + 2 x [(3 / 5) ^ 2] + 2 x [(3 / 5) ^ 3] + ... ... + [(3 / 5) ^ n] + ... ...}
= 40cm + 48cm x {1 + (3 / 5) + [(3 / 5) ^ 2] + ... ... + [(3 / 5) ^ (n - 1)] + ... ...}
= 40cm + 48cm / [1 - (3 / 5)] = 160cm
27 = 64 x (R ^ 3)
R = 0.75
so,
64 x [1 + R + (R ^ 2) + (R ^ 3) + ... ... + (R ^ n) + ... ...]
= 64 / (1 - R) = 256
Question 6
a)
40cm + 2 x (3 / 5) x 40cm = 88cm
b)
88cm + 2 x [(3 / 5) ^ 2] x 40cm = 116.8cm
c)
40cm x {1 + 2 x (3 / 5) + 2 x [(3 / 5) ^ 2] + 2 x [(3 / 5) ^ 3] + ... ... + [(3 / 5) ^ n] + ... ...}
= 40cm + 48cm x {1 + (3 / 5) + [(3 / 5) ^ 2] + ... ... + [(3 / 5) ^ (n - 1)] + ... ...}
= 40cm + 48cm / [1 - (3 / 5)] = 160cm
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