Write x2 + y2 – 18x + 8y + 5 = 0 in standard form.

Group terms and move the constant to the other side of the equation.
x2 – 18x + y2 + 8y = –5
Determine the values that need to be added to both sides of the equation.
(–18 ÷ 2)2 = 81 and (8 ÷ 2)2 = 16
Add the values to both sides of the equation.
Write each trinomial as a binomial squared, and simplify the right side.
What is the standard form of the equation of a circle given by x2 + y2 – 18x + 8y + 5 = 0?