I kinda have a question and an answer check... well heres my check.(adsbygoogle = window.adsbygoogle || []).push({});

Let f(x) = x^2 + x. For any readl number a, let Ty be the y-intrecept of the tangent line to f(a), let Nx and Ny be, respectivly, the x-intercept and y-intercepts of the normal line to f(a). SHow that a = 0 is the only value for which the area of the triangle (0,Ny),(0,0),(Nx,0) is equal to the area of triangle (0,Ty),(0,0),(Nx,0).

to attack this problem i decided since the triangles both have side (0,0),(Nx,0) in common i could just find the equations of the tangent and normal line, find the intercepts of the tangent and normal and then set them equal in magnitude. i ended up with a^2 = a/(2a +1) + a^2 + a

when i solve i get x = 0, x=-1

it seems to work out when i plot the graphs for x = -1...

but in my question it says show that a = 0 is the only possible value, am i drawing it wrong or is my prof missing something? ty

question #2...

this should be an easy question...

f(x) = x/|x| at x = 0;

the derivative do not exist, explain why. There is a skip ?

Can the definitions be modified(slightly) so that the derviative does exist at this point, if so calc the derivative. if no explain why. i need help on this question :|

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Couple questions

**Physics Forums | Science Articles, Homework Help, Discussion**