SOLUTION: . Find the value of k such that the graphs of x + 7y = 70 and y + 3 = kx are perpendicular.

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Question 313263: . Find the value of k such that the graphs of x + 7y = 70 and y + 3 = kx are perpendicular.
Answer by OmniMaestra(21) About Me  (Show Source):
You can put this solution on YOUR website!
First find the slope of the known equation:
x+%2B+7y+=+70
change the equation to slope-intercept form.
solve for y, subtract x from both sides 7y+=+-x+%2B+70
Divide both sides by 7------------------7y%2F7=%28-x%2F7%29+%2B+%2870%2F7%29
Simplify into slope-intercept form------y+=+%28-1%2F7%29x+%2B+10
So the slope is -1/7. The slope of the perpendiculoar line must be the inverse reciprocal of the original. -1%2F7 becomes 7%2F1+=+7
Now solve the second equation for y. ---- y+=+kx+-3
replace k with the new slope--------------y=7x-3, so k = 7