Evaluate x^2 - 5(x - y) for x = 8 and y = 4.

Step-by-step solution

1. 1

   Substitute the given values. Replace each variable, keeping the parentheses intact: $8^2-5(8-4).$ Keeping the grouping is essential — $5$ multiplies the whole difference, not just the $8$.

2. 2

   Work inside the parentheses first. $8-4=4$, so the expression is $8^2-5(4)$.

3. 3

   Evaluate the exponent. $8^2=64$, giving $64-5(4)$. Exponents come before multiplication in the order of operations.

4. 4

   Multiply. $5(4)=20$, so the expression is $64-20$.

5. 5

   Subtract to finish. $64-20=44$.