Mathematics for IGCSE & O level - Proportion (Section 2 - No. 8)
If *y* is directly proportional to the square root of *x*, and *y* = 6 when *x* = 9, which equation correctly represents this relationship?
y = x/2
y = 2√x
y = √x
y = 6√x
설명
y=k√x, 6=k√9, 6=3k, k=2. Therefore, y=2√x.