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ALGEBRA HELP pleasee (:?
the question is
there are two ordered pairs
(5,r) (r,6)
& the slope of the line has to be 5/8
what is r ?
& r has to be the same numberrr.
2 Answers
- ?Lv 71 decade agoFavorite Answer
Your last sentence carries no meaning. However if your question requires " finding out the value of ' r ' when the slope of the line = 5/8, Then, here is the solution -
The slope of the line m = ( y2 - y1 ) / ( x2 - x1 ). In our case --
y1 = r, y2 = 6, , x1 = 5, and x2 = r,
Substituting these values in the above mentioned formula we get ----
5/8 = ( 6 - r ) divided by ( r - 5 )
=> ( 6 - r ).8 = ( r - 5 ) .5
=> 48 - 8.r = 5.r - 25
=> 48 + 25 = 5.r + 8.r
=> 13.r = 73
=> r = 73/13 = 5 . 6 1 5 ........... Answer Answer
...............................................................................................
CHECK
Substitute r = 73/13 in eqn (1) –
=> ( 6 – r ) / ( r – 5 ) = ( 6 - 73/13 ) / (73/13 - 5 )
= [ (78-73)/13 ] divided by [ (73 – 65) / 13 ]
= ( 5/13 ) / (8/13)
= 5/8 …………………. Which is the slope (given value)
Hence value of r = 73/13 is correct .
- Bob BLv 71 decade ago
For the slope to be 5/8, (6 - r) / (r - 5) must equal 5/8 (the rise over the run is 5/8).
(6 - r) / (r - 5) = 5/8
Cross-multiply:
5(r - 5) = 8(6 - r)
Multiply it out:
5r - 25 = 48 - 8r
Add 8r to both sides:
5r - 25 + 8r = 48 - 8r + 8r
or
13r - 25 = 48
Add 25 to both sides:
13r = 73
Divide both sides by 13:
r = 73/13
The points will be (5, 73/13) and (73/13, 6)
Check:
Rise: 6 - 73/13 or 78/13 - 73/13 = 5/13
Run: 73/13 - 5 or 73/13 - 65/13 = 8/13
Slope: (5/13) / (8/13)
Invert and multiply:
(5/13) * (13/8) = 5/8