What is the slope of the line whose function f satisfies f(-2)=1 and f(5)=-10?

题目

What is the slope of the line whose function f satisfies f(-2)=1 and f(5)=-10?

答案

设f(x)=kx+b,求k,就是直线的斜率.
f(-2)=-2k+b=1 一
f(5)=5k+b=-10 二
二式减一式 ：5k-(-2k)=-10-1
得出：k= -11/7
The slope of the line is -11/7