How do you solve $x^2 - 18x = 19$ by completing the square?

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Answer 1 · 2015-07-13T18:19:52

Solve: $y = x^2 - 18x - 19 = 0$

Since (a - b + c = 0), use the shortcut. The 2 real roots are: (- 1) and (-c/a = 19).

Solving by completing the squares

$x^2 - 18x + 81 = 19 + 81 = 100$
$(x - 9)^2 = 100$ --> $x - 9 = +- 10$
$x = 9 +- 10$ --> x = - 1 and x = 19.

How do you solve x^2 - 18x = 19x^2 - 18x = 19 by completing the square?