solve by Substitution
1. 3x-y=5
y=3x-5
2. 2x+8y=3
x =8-4y
2006-11-16 15:38:10 · 3 answers · asked by Anonymous in Education & Reference ➔ Homework Help
1 is an odd one.
3x - y = 5
y = 3x - 5
To solve by substitution, plug y from the second equation into the first one:
3x - y = 5
3x - (3x - 5) = 5
3x - 3x + 5 = 5
5 = 5
The x and y cancel out. What we're left with is always true - 5 always equals 5 - so the two lines you're given are actually the same line, and any (x,y) pair that solve the first will also solve the second.
2) Same idea.
2x + 8y = 3
2(8 - 4y) + 8y = 3
16 - 8y + 8y = 3
16 = 3
In this case, we end up with an impossibility - 16 never equals 3. Therefore, there are no solutions that solve both equations simultaneously, and the lines are parallel.
2006-11-16 15:56:27 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The first problem contains two equations which are same and hence it is an identity and not an equation.
2.2x+8y=3........(Equn. 1)
x=8-4y...........(Equn. 2)
Putting the value of x given in eqn 2 in equation no 1,we get
2(8-4y)+8y=3
=>16-8y+8y=3
Sorry this problem is also wrong.It cannot be solved.Be careful while sending the problems.I think you have erred in typing the problems
2006-11-17 01:05:58 · answer #2 · answered by alpha 7 · 0⤊ 0⤋
Take the solution for y from equation 1 and substitute for the y in equation 2. This will give you an equation containing only x. Then solve for the x to get the value of x. Once you have the value of x, substitute that value for x back into equation 1 to find the value of y.
2006-11-16 23:49:17 · answer #3 · answered by rscanner 6 · 0⤊ 0⤋