Find the elasticity of the demand function:

Question

pq = 42 p=$2
My professor went through this lesson really fast and I would appreciate anyone's help in explaining it.
Thank You

Answer 1

Try reading the following in compensation for the quick lesson.

http://www.economicshelp.org/blog/7019/economics/examples-of-elasticity/

and for equations/formulas:
http://study.com/academy/lesson/the-elasticity-of-demand-definition-formula-examples.html

p=price=$2
q=quantity

pq=42 means that
q(p)=42/p
dq/dp=-42/p^2
At p=2, q=42/p=21, dq/dp = -42/4=-10.5

The price elasticity of demand is then
PED(p)=(p/q) * dq/dp
=(p/(42/p))*(-42/p^2)
=-1 (for all values of p)