Explanation

We can simplify the expression using the identity:  

a³ + b³ = (a + b)(a² - ab + b²)

Here,  

a = 8.73, b = 4.27  

a + b = 13  

a² = 8.73² = 76.2129  

b² = 4.27² = 18.2329  

ab = 8.73 × 4.27 = 37.2671  

Now,  

a³ + b³ = (13)(76.2129 - 37.2671 + 18.2329)  

= 13 × (57.1787)  

≈ 743.3