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Here, .2+.2<1. So, the production surface exhibits decreasing returns to scale. Consequently, the lines between the colored areas are not equally spaced. Instead, the get farther and farther apart with increasing levels of outputs.
…this effect is more pronounced when looking at the surface from above in order to view the isoquants.
In this production function, .2+.9>1. So, the surface exhibits increasing returns to scale.
Isoquants reflect decreasing returns to scale.