If `a-b=4` and `a b=21 ,` find the value of `a^3-b^3`

Explanation

To find the value of \( a^3 - b^3 \) given that \( a - b = 4 \) and \( ab = 21 \), we can use the algebraic identity for the difference of cubes:

\[ a^3 - b^3 = (a - b)(a^2 + ab + b^2) \]

### Step 1: Calculate \( a - b \)
From the problem, we know:
...