if you draw a triangle starting from P1 and go up to the y value of P2, the change in y is equal to 6.
From that point, go to the right until you hit P2 to get a change in x of 2.
Youre basically missing the hypotenuse of this triangle that you drew. Which is where the distance formula is derived from. 6^2 + 2^2 = s^2
You get √40 = s. It appears that they want you to simplify this square root. What are the two greatest numbers that multiply to equal 40 and atleast one of them has a perfect square root? That's 10 and 4. you can perfectly take the square root of 4, so go ahead and do that. Put that 2 outside of the square root. That gives you