#### To determine

**a)**

**To find:**

The unit for dadx.

#### Answer

pound(foot)2

#### Explanation

**1) Concept:**

The unit of dfxdx=unit of f(x)unit of (x).

**2) Given:**

The units of x are feet and the units of a(x) are pound per foot.

3) **Calculation:**

To find the unit of dadx

The units of daxdx=unit of a(x)unit of x

The unit of x is feet and unit of a(x) is pound/foot.

So the unit of d(ax)dx=pound/footfoot

Hence, the unit of d(ax)dx=pound(foot)2

**Conclusion:**

Therefore, the unit of dadx=pound(foot)2

#### To determine

**b)**

**To find:**

What unit does ∫28axdx have.

#### Answer

Pounds.

#### Explanation

**1) Concept:**

The unit of measurement for ∫abfxdx is the product of unit of x & fx.

**2) Given:**

**∫28axdx**

where unit of x is in feet and unit of a(x) is pound per foot.

**3) Calculation:**

Consider ∫28axdx

Here, unit of x are feet and units of a(x) are pound per foot.

The unit of measurement for ∫abfxdx is the product of the units of x & fx.

Therefore, the unit of ∫28axdx is pounds ( (feet)(pound/feet)= pound).

**Conclusion:**

Therefore, the unit of ∫28axdx is pounds.