Question 264851: 7x-4y=-3
2x+5y=8
Found 3 solutions by mananth, ikleyn, timofer:
Answer by mananth(16949)   (Show Source):
You can put this solution on YOUR website! 7x-4y=-3 ----------1
2x+5y=8
14x-8y=-6
14x+35y=56
-43y=-62
y= -62/-43
y=1.44
substitute the value of y in the equation 1
7x=2.76
x=2.76/7
x=0.39
Answer by ikleyn(53725)  (Show Source):
You can put this solution on YOUR website! .
7x - 4y = -3
2x + 5y = 8
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The solution and the answer in the post by @mananth are incorrect.
See below my correct solution.
Your starting equation are
7x - 4y = -3 (1)
2x + 5y = 8 (2)
Let' solve the system by the Elimination method.
For it, multiply equation (1) by 2 (both sides) and multiply equation (2) by 7 (both sides).
You will get
14x - 8y = -6 (3)
14x + 35y = 56 (4)
From equation (4), subtract equation (3). The terms '14x' will cancel each other, and you will get
35y - (-8y) = 56 - (-6),
43y = 62,
y = 62/43.
To find 'x', substitute y = 62/43 in equation (2)
2x +  = 8,
2x =  =  =  .
x =  .
ANSWER. x = , y =  .
At this point the problem is solved completely.
There is no need to convert this solution in rational numbers to decimals as @mananth does.
The meaning of the problem is to get a precise solution in rational numbers,
and the problem does not ask to convert (to round) them in decimals.
Making conversion (rounding), you lose the precision.
Had the problem specially request for rounding, it would be justified.
Without a special request for rounding, in this problem it is better
to present a precise solution in rational numbers.
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I perfectly know/understand WHY @mananth makes rounding here - it is because his computer code,
which he permanently uses to generate the solution files, is programmed this way.
But having incorrect (incorrectly written) computer code is not an argument to teach students in a wrong way.
Answer by timofer(155)  (Show Source):
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