Question

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

Answer 1

`\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 = √(( x_2- x_1)^2 + ( y_2- y_1)^2) \\\\\\ d=√([-8-7]^2+[-9-(-1)]^2)\implies d=√((-8-7)^2+(-9+1)^2) \\\\\\ d=√(225+64)\implies d=√(289)\implies d=17`

Answer 2

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`