         {
             merge(
                 polynomialA:polynomial,
-                polynomialB:result)
+                polynomialB:result,
+                inverse:true)
             
             DManager.sharedInstance?.createManagedObject(
                 entityName:DPolynomial.entityName)

        {
            merge(
                polynomialA:polynomial,
                polynomialB:compare)
            
            equation.removeFromPolynomials(compare)
            DManager.sharedInstance?.delete(object:compare)

            guard
            
                let polynomials:[DPolynomial] = equation.polynomials?.array as? [DPolynomial],
                let result:DPolynomial = equation.result
            
            else
            {
