Question

Which of the following graphs of $y=f\left(x\right)$ is NOT Function?

• A.
• B.
• C.
• D.

Answer 1

Answer: (B), (C), (D)

By applying Vertical Line Test to all the graphs, we can check whichever graph is a function and whichever is not.
In first graph, there is maximum one point of intersection between the curve and the vertical line drawn. so it is function.

In all other three graphs, we see that there are more than one point of intersection between the curve and the vertical line. So, all the three graphs in options $\left(b\right),\left(c\right)$ and $\left(d\right)$ are NOT functions
In the graph of option(d), we can see that $AB||y-axis$ so the vertical line will coinside with $AB$ hence there will be infinite points of intersection between $AB$ and the vertical line hence, the graph will NOT be function.

So, graphs in options $\left(b\right),\left(c\right)$ and $\left(d\right)$ are correct answer