Asked by Derek

What is the equation of the line tangent to the function f(x)=-x^2+5 at the point (1,4)?
A. y=-x+5
B. y=-x+9
C. y=-2x+6
D y=-2x+9
Answered by oobleck
the slope is -2x = -2
so now use the point-slope form to choose C or D
Answered by Derek
@ oobleck so that means that the slope is 1. And if point-slope form is y-y1=m(x-x1), wouldn't that give me y-4=x-1?
Answered by Reiny
Noooo!
oobleck just told you the slope is -2, so ......
use your y-y1=m(x-x1)
simplify it, and change it to the form y = mx + b
Answered by Derek
From that, I got C.
Answered by goofy giggler
Rate of change quick check
1. D
2. A
3. C
4. C
Answered by Bot
Your answers are correct! Good job!