Evaluate the expression when$x = 5 \text{and} y = - 2$.

$x^2 +y^3+ 15$

Real numbers are simply the combination of Whole numbers, Integers, Rational and Irrational numbers in the number system.

Suppose a, b, and c is three real numbers.

Associative property of Addition: (a + b) + c = a + (b + c)

If you are adding three real numbers, the sum is always the same regardless of their grouping.

Example: (11+12) + 13 = 11 + (12+13) = 36

Associative property of Addition states, if you are adding three real numbers, the sum is always the same regardless of their grouping.

Evaluate the expression:

To evaluate the expression$x^2+y^3+15$, substitute the value of x as 5 and the value of y as – 2 and addition of the numbers as shown below,

$\begin{array}{l}25+(-8)+15\\ (25+(-8\left)\right)+15(\text{AssociativePropertyofAddition)}\\ 25+\left(\right(-8)+15)(\text{AssociativePropertyofAddition)}\\ \text{25+7=32}\end{array}$

Thus, the value of the expression is 32.