I saw this equation on Google GROUPS. The post date was 2004 and I can't find the person that posted it for resolution. I figured that this equation is un-solvable (I solved 7 = -8). Can anyone shed any light on this? Could the person that posted it simply have missed an operator or made a negative number positive? Does anyone have a simple change that would make this formula solvable? (It was from an 8th grade mathbook, according to the poster. I can't imagine there would be unsolvable equations at the 8th grade level).
2007-02-05 05:36:18 · 4 answers · asked by trigam41 4 in Science & Mathematics ➔ Mathematics
distribute:
7-3x = x - 8-4x
7-3x = -3x -8
7 = -8
the problem is that this equation is not valid from the start. The left hand of the equation never equals the right hand of the equation.
Or, to put it another way
y = -3x + 7 and
y = -3x - 8
are two parallel lines that never intersect.
2007-02-05 05:45:41 · answer #1 · answered by bequalming 5 · 0⤊ 0⤋
it either comes out to 15=0 or -15=0, both of which don't make sense
7-3x=x-4(2+x)
7-3x=x-8-4x
+3x +3x
7=x-8-x
+8 +8
15=x-x
15=0
or
7-3x=x-8-4x
7-3x=-8-3x
-7 -7
-3x=-15-3x
+3x +3x
0=-15
no solution
2007-02-05 13:47:46 · answer #2 · answered by biotech619 1 · 0⤊ 0⤋
No solution
7 - 3x = x - 4(2 + x)
7 - 3x = x - 8 - 4x
7 - 3x = - 3x - 8
7 - 3x + 3x = - 3x - 8 + 3x
7 = - 8
- - -- - - - - - s-
2007-02-05 13:54:24 · answer #3 · answered by SAMUEL D 7 · 0⤊ 0⤋
7-3x=x-8-4x
-3x+7-7=-3x-8-7
-3x=-3x-15
-3x+3x=-3x+3x-15
0x=-15
2007-02-05 14:10:41 · answer #4 · answered by Dave aka Spider Monkey 7 · 0⤊ 0⤋