Derivative by graphing

[dbag]

Problem states that i must find the instantaneous rate of change at x=3 and above is a picture of my solution its basically just 9/-8 and that comes out to -1.125. Is it correct?

 

[Harry_the_cat]

Your tangent is very rough but close-ish (I'd use a thinner line).
The gradient is rise/run. You have it the other way around ie shoud be -8/9 BUT count your squares again - your 9 should be an 8. So gradient is approximately -8/8 = -1.

 

[dbag]

thanks