SOLUTION: 9. A friend say the slope of a line passing through (1,7) and (3,9) is equal to the ratio 1-3/7-9. What is your friend's error? Please explain to me how you got the answer after

Algebra ->  Test -> SOLUTION: 9. A friend say the slope of a line passing through (1,7) and (3,9) is equal to the ratio 1-3/7-9. What is your friend's error? Please explain to me how you got the answer after      Log On


   

Question 781894: 9. A friend say the slope of a line passing through (1,7) and (3,9) is equal to the ratio 1-3/7-9. What is your friend's error?
Please explain to me how you got the answer afterwards. Thanks :)
Found 2 solutions by Alan3354, MathTherapy:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
9. A friend say the slope of a line passing through (1,7) and (3,9) is equal to the ratio 1-3/7-9. What is your friend's error?
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slope = diffy/diffx
He has diffx/diffy, the inverse.
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Plus, someone should add parentheses --> (3-1)/(9-7)
Not 1 - (3/7) - 9

Answer by MathTherapy(10557) About Me  (Show Source):
You can put this solution on YOUR website!
9. A friend say the slope of a line passing through (1,7) and (3,9) is equal to the ratio 1-3/7-9. What is your friend's error?
Please explain to me how you got the answer afterwards. Thanks :)

The slope is calculated as the RISE%2FRUN, or %28THE_CHANGE_IN_Y%29%2F%28THE_CHANGE_IN_X%29, not the RUN%2FRISE.

As a result, it should've been highlight_green%28%287+-+9%29%2F%281+-+3%29%29. From here you can calculate the slope, if you so wish.

Your problem needed to be stated differently, in that you need to use parentheses. In other words, you should've written:
(1 - 3)/(7 - 9).