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Explanation:
Apply the distance formula.
[tex]d = \sqrt{ (x_1-x_2)^2+(y_1-y_2)^2}\\\\d = \sqrt{ (-1-1)^2+(4-(-1))^2}\\\\d = \sqrt{ (-1-1)^2+(4+1)^2}\\\\d = \sqrt{ (-2)^2+(5)^2}\\\\d = \sqrt{ 4+25}\\\\d = \sqrt{ 29}\\\\d \approx 5.38516\\\\d \approx 5.39\\\\[/tex]
You could also use the pythagorean theorem which is what the distance formula is based off of.