Try to get $m^2$ alone on one side of the equation. What can you divide both sides by to remove the $5$ and $n$ from $m^2$?

Once you have an equation like $m^2 = \text{(expression)}$, what operation do you use to solve for $m$? Remember that $m$ is positive.

Choose simple positive values, such as $k = 20$ and $n = 1$, and keep them in mind. (Any positive values will work; using easy numbers just makes checking simpler.)

In Desmos, use $x$ for $m$. Enter the functions

• $y = 5x^2 \cdot n$ (replace $n$ with your chosen value)
• $y = k$ (replace $k$ with your chosen value)

Find the positive $x$-value where the two graphs intersect; this $x$ is the value of $m$ that satisfies the original equation for your chosen $k$ and $n$.

For each option, type its right-hand side in Desmos, replacing $k$ and $n$ with the specific numbers you chose. Compare each result with the positive intersection $x$-value from Step 2. The correct formula is the one that produces that same $m$-value.

You are given the equation

and asked to write $m$ only in terms of $k$ and $n$. That means you need to rearrange the equation so it becomes m = \text{(expression with only k$and$n)}.

Right now, $m^2$ is being multiplied by $5$ and by $n$.

To isolate $m^2$, divide both sides of the equation by $5n$:

On the right side, the $5$ and $n$ cancel, leaving

So you have $m^2$ written in terms of $k$ and $n$.

To go from $m^2$ to $m$, take the square root of both sides:

Since $m$ is given to be positive, $\sqrt{m^2} = m$ (you do not take the negative root).

So the correct expression is