Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
Trending News
Alegra solutions for these questions?
1. Explain how to apply elimination in solving a system of equations.
2. Explain how to apply substitution in solving a system of equations.
3. Demonstrate each technique in solving the system
1. 3x + 9y = 12
2. 5x - 4y = 3
2 Answers
- AdmireLv 78 years agoFavorite Answer
Explain by demonstration
Substitution
From 1, x = (12 - 9y)/3 = 4 - 3y.....Put this in '2'
5(4 - 3y) - 4y = 3
20 - 15y - 4y = 3
19y = 17
y = 17/19
x = 4 - 3*17/19 = 25/19
Elimination
Eliminate x by multiplying '1' by 5 and '2' by 3 to get
15x + 45y = 60
15x - 12y = 9 ...Now Subtract
-------------------
0x + 57y = 51
y = 51/57 = 17/19....Put this in '1'
3x + 9*17/19 = 12
3x = 12 - 153/19 = 75/19
x = 75/19 * 1/3 = 25/19
(25/19, 17/19)
- JuanLv 68 years ago
3x + 9y = 12
9y = 12 - 3x
3y = 4 - x
y = (4 - x) / 3
5x - 4y = 3
-4y = 3 - 5x
4y = 5x - 3
y = (5x - 3) / 4
(4 - x) / 3 = (5x - 3) / 4
4 * (4 - x) = 3 * (5x - 3)
16 - 4x = 15x - 9
16 = 19x - 9
25 = 19x
x = (25/19)
3*(25/19) + 9y = 12
(75/19) + 9y = 12
(75/19) + 9y = (228/19)
9y = (153/19)
y = (17/19)
5 * (25/19) - 4y = 3
(125/19) - 4y = 3
(125/19) - 4y = (57/19)
-4y = -68/19
4y = 68/19
y = (17/19)
x = (25/19); y = (17/19) or [(25/19),(17/19)]
