Q.A linear demand function is given as $P = 100 - 2Q$. Find the Y-intercept and the X-intercept of this demand line, and state what each represents economically.

The Y-intercept is found by setting Q = 0 and the X-intercept by setting P = 0 in the given demand equation. …

Step 1 — Y-intercept (set $Q = 0$): $P = 100 - 2(0) = 100$. This is the choke price — the highest price at which quantity demanded becomes zero.

Step 2 — X-intercept (set $P = 0$): $0 = 100 - 2Q \Rightarrow 2Q = 100 \Rightarrow Q = 50$. This is the saturation quantity — the quantity that would be demanded if the good cost nothing. …

Confusing which intercept is which — the Y-intercept always comes from setting the OTHER variable (X, here Q) to zero, not the Y-variable itself; forgetting to state the economic meani …