Question

Roni wants to write an equation to represent a proportional relationship that has a constant of proportionality equal to 7/25. She writes the equation y = x + 7/25. What error is Roni making?

Answer 1

Roni did not make use of the equation for a proportional relationship.

Explanation:

For some constant of proportionality k, y is proportional to x if x and y satisfy the equation ...

y = kx

Roni knows k=7/25, but she did not use this equation. She added instead of multiplying, so did not end with an equation expressing a proportional relation.

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y = (7/25)x