https://www.gregmat.com/quizzes/quiz/im-overwhelmed-algebra-progress-quiz-4-version-2 (Question 4)
Hi again. Don’t we know that the value for b is negative 8 since the original formula has a negative b value?
If b = -8, then you have x^2 +8x + 16 = (x + 4)^2 = 0, which has only one solution at
x = -4.
Likewise, if b = 8, then you have x^2 - 8x + 16 = (x - 4)^2 = 0, which also has only one solution at x = 4.
Both work.