(x – r_1)*(x – r_2) = x^2 – (r_1 + r_2)*x + r_1 * r_2.

(2) If the instructions read “Factor x^2–2*x–63”, the required response is

“x^2–2*x–63 = (x – 9)*(x + 7)”, and the two factors are (x – 9) and (x + 7). There is no issue about whether these factors are negative or positive: the factor (x – 9) is positive exactly if x > 9, while the factor (x – 9) is negative exactly if x < 9. If the instructions read "Factor x^2-2*x-63", there is no issue of solutions; only equations have solutions; expressions do not have solutions. The equation x^2-2*x-63=0 has the two solutions x = 9 and x = -7; the equation (x – 9)*(x + 7) = 37 has two different solutions.