Answer:
a₄ = -9
Step-by-step explanation:
Given:
a₁ = 5
aₙ₊₁ = 2aₙ - 7
To calculate a₄ we would use 3 for n.
aₙ₊₁ = 2aₙ - 7
a₃₊₁ = 2a₃ - 7
a₄ = 2a₃ - 7
However we don't know a₃. Let's start from the bottom.
a₁ = 5
a₂ = a₁₊₁ = 2a₁ - 7
= 2(5) - 7
= 10 - 7
= 3
a₃ = a₂₊₁ = 2a₂ - 7
= 2(3) - 7
= 6 - 7
= -1
a₄ = a₃₊₁ = 2a₃ - 7
= 2(-1) - 7
= -2 - 7
= -9
