Question 444146: 6x - y = 39
6x + 7y=33
Found 3 solutions by mananth, ikleyn, josgarithmetic:
Answer by mananth(16949)   (Show Source):
You can put this solution on YOUR website! 6x-y=39 .............1
6x+7y=33 .............2
Eliminate y
multiply (1)by 7
Multiply (2) by 1
42x-7y=273
6x+7y=33
Add the two equations
48x=306
/48
x=6.38
plug value of x in (1)
6x-1y=39
38.25- y=39
-y=39-38.25
-y=0.75
y=-0.75
Answer by ikleyn(53570)  (Show Source):
You can put this solution on YOUR website! .
6x - y = 39
6x + 7y=33
~~~~~~~~~~~~~~~~~~~
As I look at the solution in the post by @matanth, his solution evokes a feeling of protest in me,
because, strictly speaking, it is incorrect.
Using decimal numbers with two digits after the decimal dot, he found the solution x = 6.38, y = -0.75.
While the 'y'-value is precise, 'x'-value is approximate.
The exact 'x'-value is 6.375, so the exact solution is (x,y) = (6.375,-0.75).
As I see, the computer code, which @manath uses for his calculations, is very restricted
and does not make a selection, which form to use - in rational numbers or in decimals,
and always prints the output decimals with 2 decimal digits.
In many cases, it leads to incorrect/erroneous solution.
A good code (I mean, a truly good code) must be much smarter and much more flexible,
with built-in-brain.
Answer by josgarithmetic(39720)  (Show Source):
|
|
|
