Need help solving a substitution math problem. It's 4x + 2y = 8 and y = -2x + 4.?

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Need help solving a substitution math problem. It's 4x + 2y = 8 and y = -2x + 4.?

2007-02-14 09:39:55 · 4 answers · asked by LaLa 2 in Education & Reference ➔ Homework Help

4 answers

4x + 2y = 8 (y = -2x +4)
4x + 2(-2x + 4) = 8
4x + (-4x) + 8 = 8
4x - 4x + 8 = 8
x + 8 = 8
x = 0

2007-02-14 09:47:06 · answer #1 · answered by Anonymous · 0⤊ 0⤋

you know what y is from the second equation.
1. Plug y from the 2nd equation into the first
2. that would give you 4x + 2(-2x +4) = 8

you can solve from there...

2007-02-14 17:48:26 · answer #2 · answered by princesskae4 2 · 0⤊ 0⤋

lets begin:
8 = 4x + 2y
8 (- 4x) = 4x (- 4x) + 2y
8 - 4x = 2y
1/2 x (8 - 4x) = 1/2 x (2y)
4 - 2x = y
-2x + 4 = y

yes you are correct on value of y

2007-02-14 17:48:56 · answer #3 · answered by ? 7 · 0⤊ 0⤋

4x + 2y = 8
2x + y = 4
y = 4 - 2x

2007-02-14 17:49:36 · answer #4 · answered by Han J Solo 2 · 0⤊ 0⤋