Question

The demand function for a certain item is x = 35(sqrt(32-p^2))
---Evaluate the elasticity at 5. E(5)=
I don't know how to find elasticity, so i don't know how to start this problem. If someone could explain elasticity i think that i could figure it out.

Answer 1

Isn'n
Elasticity = - ddemand/dprice * P/q ?

so here
elasticity= - dx/dp * p/x

I assume you can take the derivative, put p=5 (and x(5)) and compute E.

Answer 2

dx/dp = 35*(1/2)*(-2p)/sqrt(32-p^2)
= -35/sqrt(32-p^2)

Now evaluate E(x) = -(p/x)* (dx/dp)
@ p=5
x(5) = 35 sqrt 5
and put it all together.

A few numbers will cancel, simplifying the result.