ΔQΔY×YQ\mathrm {\frac{ΔQ}{ΔY}\times \frac{Y}{Q}}ΔYΔQ×QY
ΔQΔP×PQ\mathrm {\frac{ΔQ}{ΔP}\times \frac{P}{Q}}ΔPΔQ×QP
ΔQQ×ΔPP\mathrm {\frac{ΔQ}{Q}\times \frac{ΔP}{P}}QΔQ×PΔP
ΔQxΔPy×PyPx\mathrm {\frac{ΔQ_x}{ΔP_y}\times \frac{P_y}{P_x}}ΔPyΔQx×PxPy