P2 PS 41

[chiungfen]

41.In the infinite sequence a1, a2, a3, . . . , an, . . . , each term after the first is equal to twice the previous term. If a5 - a2 = 12, what is the value of a1 ?


sorry, .......這題是可以算出答案是(E), 但我手邊沒有答案的正確數字，是否
肯請好心人士幫忙求解


這題花了我好久時間喔~~~還是不會算啦

[chiungfen]

幫幫忙

[aqboy[origen]]

a5=2*a4
=4*a3
=8*a2

a5-a2=7*a2=12

a2=12/7

a1=12/7/2=6/7

[chiungfen]

THANKS aqboy~~~