private boolean isSimplified(AlgebraicParticle expr){
		if(expr.exponent() != 1)return false;
		else if(expr instanceof Number) return true;
		else if(expr instanceof Variable && expr.sign()) return true;
		else if(expr instanceof Fraction && ((Fraction)expr).isSimplified()) return true;
		else if(expr instanceof MixedNumber && ((MixedNumber)expr).isSimplified()) return true;
		else return false;
	}