F5 Maths

No.

Since y ∝ x, then y = kx
where k is a constant.

y + 2
= kx + 2
= k(x + 3) - 3k + 2

Unless -3k + 2 = 0
y + 2 ≠ constant * (x + 3)

But when -3k + 2 = 0
k = 2/3 and y = 2x/3
y > x only holds when both x and y are negative.

Hence (y + 2) does NOT vary directly as (x + 3).

2012-06-26 20:50:00 補充：
發問時點數已扣除，刪除問題只會損人不利己。