2015 · Q20
If k=x-y+2z where -2 ≤ x ≤ 1, -1 ≤ y ≤ 2 and 3 ≤ z ≤ 6, then which one of the following is correct ?
Elementary MathematicsTime, Speed and Distance
- A0 ≤ k ≤ 9
- B5 ≤ k ≤ 11
- C2 ≤ k ≤ 14
- D2 ≤ k ≤ 11
Explanation
k = x - y + 2z is minimized at x = -2, y = 2, z = 3 (k = 2) and maximized at x = 1, y = -1, z = 6 (k = 14). Hence 2 <= k <= 14, option (c).