What is the slope of the line whose function f satisfies f(-2)=1 and f(5)=-10?
问题描述:
What is the slope of the line whose function f satisfies f(-2)=1 and f(5)=-10?
答
从题目我们可以得出,这是求直线的斜率,所以函数f是一次项。故设f(x)=kx+b。代入已知条件得
f(-2)=-2k+b=1 ⑴
f(5)=5k+b=-10 ⑵
联立方程 ⑴和 ⑵,求得
k= -11/7
即 the slope of the line is -11/7.
答
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