The expression that is most useful for finding the year where the population was at a minimum would be 8(x − 9)² + 216.
Given expression 8x² − 144x + 864 is used to approximate a small town's population in thousands from 1998 to 2018, where x represents the number of years since 1998.
<h3>What is a quadratic equation?</h3>
A quadratic equation is the second-order degree algebraic expression in a variable. the standard form of this expression is ax² + bx + c = 0 where a. b are coefficients and x is the variable and c is a constant.
Given expression is 8x² − 144x + 864
Let y = 8x² − 144x + 864
also, y - 864 = 8x² - 144x
by Extracting common factor 8 on the right side
y - 864 = 8(x² - 18x)
Add (18/2)² on both sides, we get
y - 864 + 8(18/2)² = 8 (x² - 18x + 81²)
y - 864 + 648 = 8 (x² - 8x + 9)
on simplification
y - 216 = 8 (x - 9)²
y = 8(x - 9)² + 216
therefore, y = 8 (x - 9)² + 216
The expression that is most useful for finding the year where the population was at a minimum would be 8(x − 9)² + 216.
Learn more about a quadratic equation here:
brainly.com/question/2263981
