Calculation: Gj9Cnp - 1

S__n =

b1* ( q^ⁿ-1)

/ (q-1)

S__n =

b1* ( q^ⁿ-1)

/ (q-1)

$S_{n}$ = $\frac{b1\cdot (q^{n}-1)}{q-1}$

S__n =

q^ⁿ* b1

/ (q-1)

-

b1

/ (q-1)

$S_{n}$ = $\frac{q^{n}\cdot b1}{q-1}-\frac{b1}{q-1}$

S__n =

b1* q^ⁿ

/ (q-1)

-

b1

/ (q-1)

$S_{n}$ = $\frac{b1\cdot q^{n}}{q-1}-\frac{b1}{q-1}$