2007-06-29 05:41:45 · 10 answers · asked by Eric E 1 in Science & Mathematics ➔ Mathematics
You can't "solve using substitution" unless you either provide a second equation or the value of one of the variables.
2007-06-29 05:44:41 · answer #1 · answered by Mathematica 7 · 0⤊ 0⤋
Solve for x:
5x + 3y = 9
5x = 9 - 3y
x = (9 - 3y) / 5
x = 1.8 - 0.6y
Solve for y:
5x + 3y = 9
3y = 9 - 5x
y = (9 - 5x) / 3
y = 3 - (1 2/3)x
We cannot use substitution in this case as it will result in 0 = 0 whichever equation you use in the substitution as shown in the demonstration below. The values arrived at above will be the final answers.
(5 * [1.8 - 0.6y]) + 3y = 9
9 - 3y + 3y = 9
-3y + 3y = 9 - 9
0 = 0
2007-07-02 18:28:26 · answer #2 · answered by Jun Agruda 7 · 2⤊ 0⤋
Well, you have one equation and 2 unknows. Best you can do is express one unknown in terms of the other.
5x + 3y = 9
3y = 9 - 5x
y = 3 - 5/3 *x
Straight line with -5/3 slope and y intercept of 3
2007-06-29 05:46:16 · answer #3 · answered by nyphdinmd 7 · 0⤊ 0⤋
um dude, u need to have 2 equations with 2 variables in them to use substitution. then choose one of the equations, solve for a variable, then plug ur answer in the OTHER equation to find the first answer, then plug that numerical value in to find the other. FOR EXAMPLE:
2x + 4y = 8
8 x + 4y = 16
if i solve for x on 2x + 4y = 8
2x = 8 - 4y
x = 4 - 2y
then plug that back into the other equation
8( 4 - 2y) + 4y = 16
32 - 16y+ 4y = 16
32 - 12 y = 16
-12 y = -16
y = 16/12 or 4/3
then u plug that numerical value in to find the other value (it doesnt matter which equation u use)
2x + 4y = 8
2x + 4(4/3) = 8
2x + (16/3) = 8
2x = 8/3
x = 4/3
voila substitution
2007-06-29 05:51:20 · answer #4 · answered by her0eagle 3 · 0⤊ 0⤋
Lets assume y = k (any integer). Then the given equation becomes 5x + 3k = 9 => 5x = 9 - 3k => x = (9-3k)/5
Therefore the solution is x = (9-3k)/5 and y = k (for any integer).
2007-06-29 05:53:11 · answer #5 · answered by ping_anand 3 · 0⤊ 0⤋
one equation
2 unknowns
cant be solved has infinite solutions that is all the point of the line 5x+3y=9
2007-06-29 05:47:22 · answer #6 · answered by stiffmeister 2 · 0⤊ 0⤋
5x + 3y = 9
x = (9-3y)/5
5x + 3y = 9
y = (9-5x)/3
Since there is only 1 equation, substitution method is not possible...
2007-06-29 05:53:25 · answer #7 · answered by Prajna B 2 · 0⤊ 0⤋
There are two variables and only one equation. So, a solution is not possible.
2007-06-29 05:46:31 · answer #8 · answered by Swamy 7 · 0⤊ 0⤋
Wish I had this column when I was in school to do my work for me!
2007-06-29 05:50:30 · answer #9 · answered by Donna J 2 · 0⤊ 0⤋
For two variables you have to have two equations.
2007-06-29 06:42:15 · answer #10 · answered by MAHAANIM07 4 · 0⤊ 0⤋