대답:
# = (x ^ 2 + x-42) / (x ^ 2-4x-45 #
설명:
# ((x-6) (x + 7)) / ((x-9) (x + 5)
distributive 속성 사용
(x) + (x) + (x) + (x) + (- 6) -9) (x) + (- 9) (5) #
# = (x ^ 2 + 7x-6x-42) / (x ^ 2 + 5x-9x-45) #
# = (x ^ 2 + x-42) / (x ^ 2-4x-45 #
# = (x ^ 2 + x-42) / (x ^ 2-4x - 45 #
