The demand and supply equation for a certain item are given by?

Question

The demand and supply equation for a certain item are given by
D = – 5p + 40
S = – p2 + 30 p – 8
Find the equilibrium price.

Answer 1

Equilibrium is when D = S

So

-5p+40=-p^2+30p-8
or
p^2-35p+48=0

The quadratic solutions are p=33.57 and p=1.43
p=33.57 won't work as it causes negative demand.

So the solution is p = 1.43