(2B.14) If a1 = 5 and r = ‒3, write the first four terms of the geometric sequence. A. 5, 15, 45, 135 B. 5, ‒15, 45, ‒135 C. 5, ‒10, 15, ‒20 D.

Answer 1

In a geometric sequence, a_n = a₁r^n-1. Since you have a₁ and r, you can generate a₂ as

a₂ = a₁r^2-1 = a₁r¹ = (5)(-3) = -15

Similarly,

a₃ = a₁r^3-1 = a₁r² = (5)(-3)² = 45

Finally,

a₄ = a₁r^4-1 = a₁r³ = (5)(-3)³ = -135