SOLUTION: How do I solve this system using elimination? In steps please. 6/x-3/y=-4 and 9/x+9/y=21

Algebra.Com
Question 930458: How do I solve this system using elimination? In steps please.
6/x-3/y=-4 and 9/x+9/y=21
Found 3 solutions by Alan3354, TimothyLamb, MathTherapy:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
How do I solve this system using elimination? In steps please.
6/x-3/y=-4 and 9/x+9/y=21
---
Sub for 1/x and 1/y, r & s will work
6r - 3s = -4
3r + 3s = 7 (divided by 3)
------------------------------- Add
Then sub back.
Answer by TimothyLamb(4379)   (Show Source): You can put this solution on YOUR website!
6/x - 3/y = -4
9/x + 9/y = 21
---
6y/xy - 3x/xy = -4
6y - 3x = -4xy
---
9/x + 9/y = 21
9y/xy + 9x/xy = 21
9y + 9x = 21xy
---
6y - 3x = -4xy
9y + 9x = 21xy
---
21(6y - 3x = -4xy)
4(9y + 9x = 21xy)
---
21*6y - 21*3x = -21*4xy
4*9y + 4*9x = 4*21xy
---
add the two equations:
---
21*6y + 4*9y - 21*3x + 4*9x = 0
(21*6 + 4*9)y - (21*3 + 4*9)x = 0
162y - 99x = 0
162y = 99x
---
answer:
y = (99/162)x
---
Solve and graph linear equations:
https://sooeet.com/math/linear-equation-solver.php
---
Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
---
Convert fractions, decimals, and percents:
https://sooeet.com/math/fraction-decimal-percent.php
---
Calculate and graph the linear regression of any data set:
https://sooeet.com/math/linear-regression.php
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

How do I solve this system using elimination? In steps please.
6/x-3/y=-4 and 9/x+9/y=21
Let , and 

Then:

 becomes: 6a – 3b = - 4 ------- eq (i)

 becomes: 9a + 9b = 21_____3(3a + 3b) = 3(7)_____3a + 3b = 7 ---------- eq (ii)

9a = 3 --------- Adding eqs (ii) &(i)

, or 



 --------- Substituting 1/3 for a in eq (i)

2 – 3b =  – 4 

– 3b = – 4 – 2 

– 3b =  – 6

, or 



Since , then , or 

Now, since , then 



Since b = 2, then 

Now, since , then 

You can do the check!! 

===================

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

RELATED QUESTIONS


Using the elimination method, solve the system.

x-y+z=-6
2x-y+2z=9... (answered by ankor@dixie-net.com)

-6X = 18 - Y 
9 = -3X - 8Y
  How do I solve x and y using the elimination... (answered by mananth)

-4x+9y=9 
    x-3y=-6 
I have to solve for x and y using... (answered by Alan3354,Fombitz)

How do I solve the following system of equation using matrices?
x-3y+z= -21
2x-y+z=-9... (answered by ccs2011)

simplify and solve the system using elimination

2(x-4) +3(y+2) =-8
4(x+1) +5(y-1)=... (answered by Edwin McCravy)

How do I solve for X and Y using elimination?

-x+4y=10... (answered by Alan3354)

how do i solve this equation using either substitution or elimination
y=x+4
y=3x

 (answered by timvanswearingen)

i need help with the following questions PLEASE!!!!

Solve using the multiplication... (answered by solver91311)

Please solve the system of equation for all variables using a matrix.
{{{-2x+y=-4}}}... (answered by stanbon,budge)