silmultaneous equation.
3x + 2y = 8
x - 3y = 23
2007-01-17 08:35:30 · 7 answers · asked by star 2 in Science & Mathematics ➔ Mathematics
Using the substitution method:
Solve for x using the second equation.
x = 3y + 23
Insert 3y + 23 into the first equation.
3(3y + 23) + 2y = 8
Simplify
9y+69+2y = 8
11y + 69 = 8
Solve for y
11y = -61
y = -61/11
Substitute -61/11 for y into either equation.
x -3*(-61/11) = 23
x +183/11 = 23
Solve for x
x = 23-183/11 = 70/11
x = 70/11, y = -61/11
2007-01-17 08:47:09 · answer #1 · answered by mortgagelns 3 · 0⤊ 0⤋
What you need to do for these equations is pick either variable (x or y, it doesn't matter) and solve for it in one of the equations (against doesn't matter which one).
So for example, let's solve for x in the second equation. You get x - 3y = 23. Now you add 3y to both sides. You get x = 3y + 23. Now you know that for both equations, this expression must be true. So now you take your value for x and plug it into the FIRST equation. You get 3(3y + 23) + 2y = 8. Now you have gotten rid of x, and have the first equation in terms of y only! You can solve for y. You get 9y + 2y = 8/3 - 69. So now you get some value for y and you know what y is. Now you take the numerical value for y and plug it back into the SECOND equation. Then you have the second equation in terms of x only, and you can get a numerical value for x.
2007-01-17 16:41:43 · answer #2 · answered by Anonymous · 1⤊ 0⤋
Let's solve this by elimination.
3x + 2y = 8
x - 3y = 23
Multiply the second equation by (-3), to get
3x + 2y = 8
-3x + 9y = -69
Add the two equations together. Note that the 3x and -3x will cancel each other out.
2y + 9y = 8 + (-69)
11y = -61
y = (-61/11)
Now, we solve for the other variable by elimination as well.
3x + 2y = 8
x - 3y = 23
Multiply the first equation by 3, and the second equation by 2.
9x + 6y = 24
2x - 6y = 46
Add the equations together
(9x + 2x) = 70
11x = 70
x = 70/11
Therefore, your solutions are
x = 70/11
y = -61/11
2007-01-17 16:40:36 · answer #3 · answered by Puggy 7 · 1⤊ 0⤋
x - 3y = 23
x = 23 + 3y
3(23 + 3y) + 2y = 8
69 + 9y + 2y = 8
11y = 8 - 69 = -61
y = -61/11 = 5.545
so...
x = 23 + 3y
= 23 + 3(-61/11)
= 23 - 183/11
x = 6.364
2007-01-17 16:48:40 · answer #4 · answered by thubanconsulting 3 · 0⤊ 0⤋
multiply first eq. by 3, and second by 2... and add them up...
3(3x + 2y = 8) ---> 9x + 6y = 24
2(x - 3y = 23) ---> 2x - 6y = 46
--------------------
11x = 70 --> x = 70/11
and calculate the "y" by putting this "x" value to any one of the equations...
2007-01-17 16:45:10 · answer #5 · answered by chirkhin 2 · 0⤊ 0⤋
Im not sure but I think its 4x-y=31
2007-01-17 16:40:26 · answer #6 · answered by ~Zaiyonna's Mommy~ 3 · 0⤊ 1⤋
what with?
2007-01-17 16:44:14 · answer #7 · answered by LazyDaisy 3 · 0⤊ 2⤋