This is my problem:
4x+3y=a
3x+2y=b
x=?
y=?
Eqn1: 4x + 3y = a
Eqn2: 3x + 2y = b
2•Eqn1 - 3•Eqn2:
-x = 2a - 3b
x = 3b - 2a
3•Eqn1 - 4•Eqn2:
y = 3a - 4b
(x,y) = (3b - 2a,3a - 4b)
You can only solve in terms of a and b. Let's use elimination to eliminate the x and solve that way:
3 * (4x + 3y) = 3 * a
12x + 9y = 3a
4 * (3x + 2y) = 4 * b
12x + 8y = 4b
____________
0x + 1y = 3a - 4b
So y = 3a - 4b.
Plug that back into either of the original equations to solve for x. Let's use the first:
4x + 3y = a
4x + 3(3a - 4b) = a
4x + 9a - 12b = a
4x + 9a = a + 12b
4x = -8a + 12b
x = -2a + 3b
or
That's as far as you can go. Done!
Solve either equation for x or y. In this case, I used the first one.
3y =a -3x
y = a/3 – x
3x +2(a/3-x) = b
3x +2a/3 -2x =b
X + 2/3 a =b
X = b – 2/3 a
Now, you can plug in x into an equation to solve for y.
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Verified answer
Eqn1: 4x + 3y = a
Eqn2: 3x + 2y = b
2•Eqn1 - 3•Eqn2:
-x = 2a - 3b
x = 3b - 2a
3•Eqn1 - 4•Eqn2:
y = 3a - 4b
(x,y) = (3b - 2a,3a - 4b)
You can only solve in terms of a and b. Let's use elimination to eliminate the x and solve that way:
3 * (4x + 3y) = 3 * a
12x + 9y = 3a
4 * (3x + 2y) = 4 * b
12x + 8y = 4b
12x + 9y = 3a
12x + 8y = 4b
____________
0x + 1y = 3a - 4b
So y = 3a - 4b.
Plug that back into either of the original equations to solve for x. Let's use the first:
4x + 3y = a
4x + 3(3a - 4b) = a
4x + 9a - 12b = a
4x + 9a = a + 12b
4x = -8a + 12b
x = -2a + 3b
or
x = 3b - 2a
That's as far as you can go. Done!
Solve either equation for x or y. In this case, I used the first one.
3y =a -3x
y = a/3 – x
3x +2(a/3-x) = b
3x +2a/3 -2x =b
X + 2/3 a =b
X = b – 2/3 a
Now, you can plug in x into an equation to solve for y.