关于导数数学题If the line tangent to the graph of the function f at the point (1,7)passes through the point (-2,-2)then f ' (1) is ( )A.-5 B.1 C.3 D.7 E.undefined
问题描述：
关于导数数学题
If the line tangent to the graph of the function f at the point (1,7)passes through the point (-2,-2)then f ' (1) is ( )
A.-5 B.1 C.3 D.7 E.undefined
答
在（1,7）点的切线经过点（-2,-2）
切线斜率k=(-2-7)/(-2-1)=3
所以函数在(1,7)点的导数值为3
于是f'(1)=3
选C