Solve x2 - 8x - 9 = 0. rewrite the equation so that it is of the form x2 + bx = c.

It can be noted from the given that a = 1, b = -8 and c = -9. To transpose c to the other side of the equation, all that needs to be done is to add 9 to both sides of the equation,
                        x² - 8x -9 + 9 = 0 + 9 
The answer would be,
                        x² - 8x = 9