Marcus finds that 3x2-2y2+5x+4x2+12y2-7x=7x2-10y2-2x . What error did Marcus make? He combined the terms 5x and -7x incorrectly.. He combined the terms 3x2 and 4x2 incorrectly. He combined the terms -2y2 and 12y2 incorrectly. He subtracted the polynomials instead of adding.
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