A function is considered proportional if it can be expressed in the form \( y = kx \), where \( k \) is a constant. This means that for every value of \( x \), the value of \( y \) must be a constant multiple of \( x \).
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Function 1:
- \( x = 1 \), \( y = 2 \) (Ratio \( \frac{y}{x} = 2 \))
- \( x = 2 \), \( y = 4 \) (Ratio \( \frac{y}{x} = 2 \))
- \( x = 3 \), \( y = 6 \) (Ratio \( \frac{y}{x} = 2 \))
In Function 1, the ratio \( \frac{y}{x} \) is always 2, which means this function is proportional.
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Function 2:
- \( x = 1 \), \( y = 2 \) (Ratio \( \frac{y}{x} = 2 \))
- \( x = 2 \), \( y = 3 \) (Ratio \( \frac{y}{x} = 1.5 \))
- \( x = 3 \), \( y = 4 \) (Ratio \( \frac{y}{x} = \frac{4}{3} \approx 1.33 \))
In Function 2, the ratios are not constant. Therefore, this function is not proportional.
Conclusion: Function 1 is proportional.