Question

If using the method of completing the square to solve the quadratic equation

x² - 19x39 = 0, which number would have to be added to "complete the
square"?

Answer 1

below

Explanation:

x^2 - 19x ± 39 take 1/2 of the 'x' coefficient square it and add and subtract it

x^2 - 19x + 90.25 - 90.25 ±39

(x-9.5)^2 - 90.25 ±39 so I guess the answer is 90.25