Question

Which equation shows direct variation?

Answer 1

Direct variation (y varies directly with x) means the equation can be written as
y = kx
for some constant k (k ≠ 0). Equivalently y/x = k is constant.

So any equation that can be rearranged to that form shows direct variation. Examples:
- y = 4x (k = 4)
- 5x = y (k = 5)
- x = 0.2y → y = 5x (k = 5)

Non-examples:
- y = 3x + 2 (has a nonzero intercept)
- y = 3/x (inverse variation)
- y = 2x^2 (unless you mean “varies directly as x^2,” which is a different statement: y = kx^n is direct variation with power n)

If you have specific equations, paste them and I’ll tell which one(s) show direct variation.