The elimination and substitution methods can also be used to solve systems of quadratic equations.

Solve the following system of quadratic supply and demand equations, using the substitution method.

Solving (4.38) for P in terms of Q,

Substituting (4.40) for P in the other equation (4.39),

Using the quadratic formula from Section 3.5 to solve for Q,

Since both P and Q are restricted to positive values in economics, Q = 3. Substituting Q = 3 in (4.38), (4.39), or (4.40),

Transcribed Image Text:

- Supply: P 3Q + 10Q-5=0 (4.38)