Question

Find the difference between (7,-1) and (-8,-9)

Answer 1

For this case we have that by definition, the distance between two points is given by:

$d = \sqrt {(x_ {2} -x_ {1}) ^ 2+ (y_ {2} -y_ {1}) ^ 2}$

According to the data we have:

$(x_ {1}, y_ {1}) :( 7, -1)\\(x_ {2}, y_ {2}): (- 8, -9)$

Substituting:

$d = \sqrt {(- 8-7) ^ 2 + (- 9 - (- 1)) ^ 2}\\d = \sqrt {(- 15) ^ 2 + (- 9 + 1) ^ 2}\\d = \sqrt {(- 15) ^ 2 + (- 8) ^ 2}\\d = \sqrt {225 + 64}\\d = \sqrt {289}\\d = 17$

Thus, the difference or distance between the points is 17

Answer:

$d = 17$

Answer 2

$\bf ~~~~~~~~~~~~\textit{distance between 2 points} \\\\ (\stackrel{x_1}{7}~,~\stackrel{y_1}{-1})\qquad (\stackrel{x_2}{-8}~,~\stackrel{y_2}{-9})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ d=\sqrt{[-8-7]^2+[-9-(-1)]^2}\implies d=\sqrt{(-8-7)^2+(-9+1)^2} \\\\\\ d=\sqrt{225+64}\implies d=\sqrt{289}\implies d=17$