SOLUTION: I am doing something wrong but i don't know what. My equations are x-5y = 15 and 4x-3y+26 , i multiplied the first equation by -4, then got -23y = 86 . What did i do wrong? Thanks

Algebra.Com
Question 816099: I am doing something wrong but i don't know what. My equations are x-5y = 15 and 4x-3y+26 , i multiplied the first equation by -4, then got -23y = 86 . What did i do wrong? Thanks
Found 3 solutions by algebrahouse.com, josgarithmetic, MathTherapy:
Answer by algebrahouse.com(1659)   (Show Source): You can put this solution on YOUR website!
x - 5y = 15
4x - 3y = 26

-4x + 20y = -60 {multiplied first equation by -4}
4x - 3y = 26 {second equation stays the same}
------------
17y = -34 {added the two equations}
y = -2 {divided each side by 17}

x - 5y = 15 {first equation}
x - 5(-2) = 15 {substituted -2, for y, into first equation}
x + 10 = 15 {multiplied}
x = 5 {subtracted 10 from each side}

x = 5 and y = -2

For more help from me, visit: www.algebrahouse.com
Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
System:
-----------------
x-5y=15
---------------
4x-3y=26 (not exactly what you wrote, so not really sure)
----------------


Multiply first equation by -4:
-------------------------
-4x+20y=-60
----------------
4x-3y=26
----------------------

ADD the left hand members and add the right hand members:

Simple to solve as .
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

I am doing something wrong but i don't know what. My equations are x-5y = 15 and 4x-3y+26 , i multiplied the first equation by -4, then got -23y = 86 . What did i do wrong? Thanks 



   x -  5y =   15 ------ eq (i)

  4x -  3y =   26 ------ eq (ii)

- 4x + 20y = - 60 ----- Multiplying eq (i) by - 4 ----- eq (iii)

       17y = - 34 ---- ADDING eqs (iii) & (ii)

Solve for y and you should get: 

Do a check after finding x!! 



Send comments, “thank-yous,” and inquiries to “D” at MathMadEzy@aol.com.

Further help is available, online or in-person,for a fee, obviously. 



For FREE info and answers to questions about the ASVAB exam, the NYS 3 – 8 city/state wide exams, 

GENERAL MATH QUESTIONS, MATH HOMEWORK QUESTIONS, or MATH QUESTIONS related to the Regents Integrated Algebra,

Regents Geometry, Regents Algebra 2/Trigonometry, SHSAT, COOP/HSPT/TACHS, PSAT, SAT, ACT, SSAT/ISEE, GRE, CLEP,

and the GED, you can visit: http://asvabstudyzone.freeforums.net/. 

RELATED QUESTIONS


 I have tried to solve this problem but when I check it I'm wrong! I'm stumped and don't... (answered by ReadingBoosters,stanbon)

Ok, I just submitted this question so I am sorry for re-submitting it.
x+7y=8
x=6-7y
I  (answered by checkley77)

Ok so we are doing these problems where you have to find x and y and the equations are... (answered by KMST)

	Solve by substitution or elimination method: 

           4x – 5y = 14... (answered by solver91311)

Hi, I can't seem to get the answer for this equation: -x-(13+4x)=-3(5-9x)+2

I have... (answered by KnightOwlTutor)

Hi, I can't seem to get the answer for this equation: -x-(13+4x)=-3(5-9x)+2

I have... (answered by tutor_paul)

3/4x + 2/3y=7
3/5x - 1/2y=18
solve by elimination or substitution

I have done this... (answered by scott8148)

In the following problem I am trying to solve for x but something isnt working right when  (answered by jim_thompson5910)

i want to solve thisimultaneous equation 5x-5y=5,4x-3y=25

i took the first equation... (answered by checkley77,ankor@dixie-net.com)