the first term of a geometric series is 1,the nth term is 128 and the sum of the n terms is 256 find the common ratio and the number of terms.
lets call the ratio q, ok?
the sum of the first term+the second term+.....+the nth term=a1*(qn-1)/(q-1). a1=1, so the sum=(qn-1)/(q-1). we know the nth term is 128, so qn-1=128, so qn=128*q
the series is impossible