Find the 4th term of the sequence below.

Question

a₁=3, a_n=−4a_n-1

Answer 1

a1 = 3

an= -4a(n-1)

a2 = -4a1 = -4(3) = -12

a3 = -4a2 = -4(-12) = 48

a4 = -4a3 = -4(48) = -192

Answer 2

Hi Brian G.,

For a₁ = 3, and a_n = -4a_n-1 , find a₂ by setting n = 2.

Then find a₃ by setting n = 3

And finally find a₄ by setting n = 4, with a₄ being the fourth term.

a₁ = 3

a₂ = -4a_2-1 = -4a₁ = -4(3) = -12

a₃ = -4a_3-1 = -4a₂ = -4(-12) = 48

a₄ = -4a_4-1 = -4a₃ = -4(48) = -192

I hope this helps, Joe.