Question 240811
"write the equation of a line that is perpendicular to the given line and that passes through the given point." -4x-8y=24; (4,-1) the opions they give you are 
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1st find the slope of the line.  Put the eqn into slope-intercept form (that means solve for y)
-4x-8y=24
-x-2y = 6
2y = -x - 6
y = (-1/2)x - 3
That's the form, y = mx + b.  m is the slope, -1/2
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The slope of all lines perpendicular is the neg recip, = +2
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Then use y = mx + b and the point to find b:
-1 = 2*4 + b
b = -9
That makes the eqn y = 2x - 9