由题意得:
y? = (1/5)x + 1,y? = (2/4)x + 1 = (1/2)x + 1。
要求 y? = -y?,即:
(1/5)x + 1 = -
解得:
(1/5)x + 1 = -(1/2)x - 1
(1/5 + 1/2)x = -2
(7/10)x = -2
x = -20/7
y? = (1/5)x + 1,y? = (2/4)x + 1 = (1/2)x + 1。
要求 y? = -y?,即:
(1/5)x + 1 = -
解得:
(1/5)x + 1 = -(1/2)x - 1
(1/5 + 1/2)x = -2
(7/10)x = -2
x = -20/7