Answer
Answer:
When
x = 1 unit,
Surface area = 22 square units.
When,
x = 3 units,
Surface area = $78$ square units.
When,
x = 5.1 units,
Surface area = $154.2$ square units.
When,
x = 10 units,
Surface area = $400$ square units.
Work Step by Step
Given formula for surface area of box = $2x^{2}+20x$
Thus, for different values of $x$, we should have different surface areas of the box.
To find out, we simply substitute the given value of $x$ in $2x^{2}+20x$.
Thus,
When
x = 1 unit,
Surface area = $2\times(1)^{2}+20(1)$ = 2+20 = 22 square units.
When,
x = 3 units,
Surface area = $2\times(3)^{2}+20(3)$ =$ 2(9) + 60 = 18+60 = 78$ square units.
When,
x = 5.1 units,
Surface area = $2\times(5.1)^{2}+20(5.1)$ =$ 2(26.01) + 102 = 52.2+102 = 154.2$ square units.
When,
x = 10 units,
Surface area = $2\times(10)^{2}+20(10)$ =$ 2(100) + 200 = 200 +200 = 400$ square units.
