Evaluate : `int ( sqrt(4-5x) ) dx`

Explanation

To evaluate the integral \( \int \sqrt{4 - 5x} \, dx \), we will follow a systematic approach using substitution. Here are the steps:

### Step 1: Substitution
Let \( t = 4 - 5x \). Then, we differentiate \( t \) with respect to \( x \):

\[ dt = -5 \, dx \quad \Rightarrow \quad dx = -\frac{dt}{5} \]
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