Use a residual plot to assess a transformed model

Let x be the explanatory variable floor area (m²) and y the response variable quarterly electricity use (kWh). Apply the square to the response variable only. Use the full fitted coefficients below. Report signed residuals to 2 decimal places; retain unrounded values until that final step

The table records floor area (m²) and quarterly electricity use (kWh) for 6 cases. Apply a square transformation to the response variable only

The fitted equation is written on the transformed coordinates. Residuals are calculated on the fitted line's own response scale: signed residual on the quarterly electricity use² (kWh²) scale

A signed residual is observed transformed response minus predicted transformed response at the same transformed explanatory coordinate

The residual plot is shown below. A horizontal zero line is included