The thermal efficiency of an air-standard Brayton cycle

The thermal efficiency of an air-standard Brayton cycle in terms of pressure ratio r_ρ and γ(= c_ρ /c_v) is given by

Thermal efficiency of air standard efficiency = 1 –	1
	(r_ρ)^γ-1/_γ

1 –	1
	r_ρ^γ-1

1 –	1
	r_ρ^γ

1 –	1
	(r_ρ)^1/_γ

1 –	1
	r_ρ^γ-1/_γ