Question 465991
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Hi,
Please keep these formulas for reference:
D = {{{sqrt ((x[1]-x[2])^2+(y[1]-y[2])^2))}}}
( -1,-1) 
( 3, -7)  D = {{{sqrt((-4)^2 + 6^2) = sqrt(52) = 7.21}}} to the nearest hundredth

Midpoint Pt(x,y):  ( {{{(x[1] + x[2])/2}}}, {{{(y[1] + y[2])/2  )}}})

( 8,-4) 
( -7,8)  M = (1/2,2)

*[tex \LARGE\ Using \ the \ standard \ slope-intercept \ form \ for \ an \ equation \ of \ a  \ line \ y = mx + b ] 
*[tex \LARGE\ where \ m \ is \ the \ slope \ and \ b \ the \ y-intercept]
 
y + x = -2  OR y = (-1/1)x-2 
y - x = -2  OR y = (1/1)x-2  Lines are perpendicular: Solpes negative reciprocals 

y = 3x + 9    |slope m = 3 and y-inteecept is Pt(0,9)

point-slope formula, {{{m =(y[2] - y[1])/(x[2] - x[1])}}} will come in handy as well

x^2 - x - 72 = 0
factoring
(x-9)(x+8)= 0
(x-9)=0
(x+8)= 0   x = 9 and x = -8 are the solutions