Mathematics for IGCSE & O level - Proportion (Section 2 - No. 12)
If *y* is directly proportional to *x* and *y* = 4 when *x* = 2, which equation represents the relationship between *x* and *y*?
y = x + 2
y = 2x
y = x - 2
y = \(\frac{1}{2}\)x
설명
y = kx. Substitute values, 4 = k(2), k=2. Thus y = 2x