DoomDude 3 years ago What does "symmetry" mean in calc?

1. henkjan

That there is a mirrorplane/point/line... The equation is similarly shaped on both sides of this mirror

2. DoomDude

but they use it like "Deduce the value of f'(1) f'(2) using symmetry." and give you a graph of

3. DoomDude

1 sec let me get the graph

4. DoomDude

f(x) = x^2

5. henkjan

symmetry axis = x=0 f`(1) = -f`(-1) f'(2) =-f'(-2) Does that help?

6. DoomDude

so is it just flipping the graph?

7. henkjan

More or less. yep

8. DoomDude

but how would flipping a graph give you a value?

9. henkjan

Because the value of the point f'(1) has a relation to the point f'(-1)..

10. henkjan

Though you need to know the value of f'(x) in point -1

11. DoomDude

12. henkjan

yes, that is what a mirrorplane does.

13. henkjan

srry, mirrorline in 2D ;P

14. DoomDude

cause in my teachers book, it says "f'(-x) = -f'(x)"

15. henkjan

Yes, that's what I said, right?

16. DoomDude

ya.. so is it that simple, just a negative sign?

17. henkjan

indeed

18. DoomDude

ok, thanks