Question

For which x-value would the graph of y=x^2-25 be below the x-axis?A. 7B.8C.5D. 4

Answer 1

`D`

Step-by-step explanation:

For the graph to be below the x-axis, means that the value of y will be negative

Now, let us substitute for the value of x:

`\begin{gathered} a)\text{ if x = 7} \\ y\text{ = 7}^2-25\text{ = 24} \\ b)\text{ if x = 8} \\ y\text{ =8}^2-25\text{ = 39} \\ c)\text{ if x = 5} \\ y\text{ = 5}^2-25\text{ = 0} \\ d)\text{ if x = 4} \\ y\text{ = 4}^2-25\text{ = -9} \end{gathered}`

From the answers obtained, we can see that y becomes negative (below x axis) when x = 4