JAMB - Mathematics (2006 - No. 35)

The solution set of the shaded area above is

y ≥ 0, y ≥ x and y + x ≤ 4

y ≤ x, y + x ≤ 4

y + x ≥ 4, y ≤ x

y ≤ x, y + x ≤ 4 and y ≥ 0

y = x implies y ≤ x
y + x = 4 implies y = 4 – x
∴y = 4 – x
∴y ≤ x, y + x ≤ 4 and y ≥ 0