JAMB - Mathematics (2003 - No. 18)
Triangle OPQ above is the solution of the inequalities
x + 1 ≥ 0, y + x ≤ 0, y - x ≥ 0
y + x ≤ 0, y - x ≥ 0, x -1 ≥ 0
x - 1 ≤ 0, y - x ≥ o, y + x ≥ 0
x - 1 ≤ 0, y + x ≤ 0, y - x ≤ 0
Giải thích
Lines bounding Δ OPQ
OQ; y - x = 0
y - x ≥ 0
PQ; x + 1 = 0
x + 1 ≥ = 0
PO; y + x = 0
y + x ≤ 0
∴ x + 1 ≥ 0, y + x ≤ 0, y - x ≥ 0
OQ; y - x = 0
y - x ≥ 0
PQ; x + 1 = 0
x + 1 ≥ = 0
PO; y + x = 0
y + x ≤ 0
∴ x + 1 ≥ 0, y + x ≤ 0, y - x ≥ 0