Answer:
C and D
Step-by-step explanation:
The residual is computed as follows:
Residual = Observed – Predicted
If the quadratic model represents satisfactorily the data, then some predicted values will be greater, other will be equal, and others will be less than the observed ones. So, the residual plot will not form a pattern and it will be scattered about the x-axis (y-axis represents residual values)
If the residuals shows a pattern (like a parabola), then the model is not satisfactory
