Question

Indicate in which of the following equations $y$ is neither directly nor inversely proportional to $x$.

• A. $3x+y=10$
• B. $x=5y$
• C. $x+y=10$
• D. $3xy=10$

Answer 1

Answer: (A), (C)

The correct options are
A $3x+y=10$
C $x+y=10$

For $x$ to be directly proportional to $y$, the equation should be in the form of $x=ky$, where $k$ is a constant.
For $x$ to be inversely proportional to $y$, the equation should be in the form of $x=\frac{k}{y}$, where $k$ is constant.
Thus, the answer is option A and option C, as these do not fulfil the above criteria.