248 A sequence, except for the first number, a number is three times the preceding number.
X5 – X2 = 39. What is value of the first number? [1/2]
叮当意见:
同意.
X5-X2=27(X2)-X2 = 26(X2)=78(X1) = 39 à X1=1/2
不知道是否是我对题目的,理解有误, except for the first number意思好象是除了第一个数以外,那么怎么还能算的出来呢?
举报
that's the first number of a geometric series.
a1 3^4 -a1 3 = 39
a1 * 78 = 39
a1 = 0.5
谢谢!
明白了。
一直是你在回答我得问题真是感谢得很!
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