ps 13
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- givemeanid
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an = 2a(n-1) - x
a5 = 2a4 - x
Now, a4 = 2a3 -x
So, a5 = 2(2a3 - x) - x
99 = 2(2 * 27 - x) - x
99 = 108 - 2x - x
3x = 9
x = 3
a5 = 2a4 - x
Now, a4 = 2a3 -x
So, a5 = 2(2a3 - x) - x
99 = 2(2 * 27 - x) - x
99 = 108 - 2x - x
3x = 9
x = 3