SOLUTION: Determine the value of r so that the line through (6, -2) and (4, r ) has a slope of -3.

Algebra ->  Linear-equations -> SOLUTION: Determine the value of r so that the line through (6, -2) and (4, r ) has a slope of -3.      Log On


   

Question 1047189: Determine the value of r so that the line through (6, -2) and (4, r ) has a slope of -3.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The basic idea is to use the slope formula to solve for r. I show how to do this below


Step 1) m+=+%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29


Step 2) -3+=+%28r-%28-2%29%29%2F%284-6%29


Step 3) -3+=+%28r%2B2%29%2F%284-6%29


Step 4) -3+=+%28r%2B2%29%2F%28-2%29


Step 5) -2%2A%28-3%29+=+-2%2A%28%28r%2B2%29%2F%28-2%29%29


Step 6) 6+=+r%2B2


Step 7) r%2B2+=+6


Step 8) r%2B2-2+=+6-2


Step 9) r+=+4


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The explanation for each step is given here


Step 1) Start with the slope formula


Step 2) Plug in the given information


Step 3) Rewrite r-%28-2%29 as r%2B2


Step 4) Simplify 4-6 to get -2


Step 5) Multiply both sides by -2 (to undo the division of -2)


Step 6) Multiply and simplify. Notice how the "-2" terms cancel on the right side


Step 7) Flip the equation


Step 8) Subtract 2 from both sides (to undo the addition of 2)


Step 9) Combine like terms


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The final answer is r+=+4