In the xy-coordinate plane, the graph of y =-x^2+9 intersects line l at (p,5) and (t,-7). What is
问题描述：
In the xy-coordinate plane, the graph of y =-x^2+9 intersects line l at (p,5) and (t,-7). What is
the least possible value of the slope of l ?
A 6
B 2
C -2
D -6
E -10
具体计算过程和答案
答
5=-p^2+9
p^2=4
p=±2
-7=-t^2+9
t^2=16
t=±4
while (2,5) and (4,-7)
slope=(-7-5)/(4-2)=-6
while (2,5) and (-4,-7)
slope=(-7-5)/(-4-2)=2
while (-2,5) and (4,-7)
slope=(-7-5)/(4+2)=-2
while (-2,5) and (-4,-7)
slope=(-7-5)/(-4+2)=6
the answer: A B C D求 the least possible value of the slope 即最小可能的斜率答案选的是D这是为什么？为什么不是E？我答案都帮你做出来了，ABCD都有可能，哪来E选项的可能在这四个答案里最小可能的斜率当然是-6了，你以为给你个-10就是最小的了？要是题目把E中的值改成-1000000000，你是不是算都不算直接选E了？你也要能求的到那个值才能选啊。E根本不可能！