Answer: Choice B
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Reason:
Subtract 3x from both sides to go from
3x+1 = 3x+2
to
1 = 2
which is always a false statement regardless of what you pick for x. Therefore, the original equation for choice B is always false and has no solution.
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Another approach:
Graph y = 3x+1 and y = 3x+2. These are parallel lines that never intersect. We need them to intersect to get a solution. This is a visual quick way to see why this system has no solution.