Question 454258: solve using substitution method
x - 5y = 17
-5x - 6y = 8
Found 3 solutions by mananth, ikleyn, MathTherapy:
Answer by mananth(16949)   (Show Source):
You can put this solution on YOUR website! x-5y=17 .............1
6y=-8-5x ---------2
/6=
y=-1.33 -0.83x
Plug the value of y in (1)
x-5(-1.33-0.83x) =17
x+6.67+ 4.17x=17
x+4.17x= 17-6.67
5.17x=10.33
/5.17
x=2
Plug the value of x in (1)
x-5y=17
1*2-5y=17
2-5y=17
-5y=15
/-5
y=-3
Answer by ikleyn(53538)  (Show Source):
You can put this solution on YOUR website! .
Linear-systems/454258: solve using substitution method
x - 5y = 17
-5x - 6y = 8
~~~~~~~~~~~~~~~~~~~~~~~~~
The way how @mananth solves the problem in his post is absolutely incorrect.
He makes tons of incorrect calculations and invites visitors follow his wrong way,
which only can lead you to the firm score of '2'.
In this case, you are lucky, because you can easy express 'x' from the first equation
x = 5y + 17.
Now substitute it into the second equation, replacing 'x' there
-5(5y+17) - 6y = 8.
Simplify and find 'y'
-25y - 85 - 6y = 8,
-25y - 6y = 8 + 85
-31y = 93,
y =  = -3.
Now calculate 'x' from that expression which you got above from the first equation
x = 5y + 17 = 5*(-3)+17 = -15 + 17 = 2.
ANSWER. x = 2, y = -3.
Solved correctly.
Ignore the post by @mananth and never even try to solve equations in the way he does.
Answer by MathTherapy(10680)  (Show Source):
You can put this solution on YOUR website!
solve using substitution method
x - 5y = 17
-5x - 6y = 8
This is a real LAUGH! Why on earth would someone choose to SOLVE for a variable that'll create FRACTIONS - which most people hate,
and which we normally GET RID OF when solving an equation - when a perfectly-stated equation, in eq (i), already has a variable
with a coefficient of 1? This ABSOLUTELY makes NO SENSE, at all!!!
I know another person on this site, who has done the EXACT thing in some, maybe ALL, of her responses!! I wonder who taught them
these RIDICULOUS and NONSENSICAL solving techniques.
This may be one of the reasons why some people FEAR mathematics! I would, if I ever asked for help, and received this response!!
x - 5y = 17_____x = 17 + 5y ----- eq (i)
Isn't this what's needed to now substitute in eq (ii), so that the value of y can be determined, and then x, subsequently?
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