WIP #1056 in diophantinePolynomial only call QuadraticSolver.solve

- suggested by @Mangara
- `QuadraticSolver.solve` already defers to `ParabolicSolver`

Author: axkr

symja_android_library/matheclipse-core/src/main/java/org/matheclipse/core/builtin/NumberTheory.java

@@ -96,7 +96,6 @@
 import io.github.mangara.diophantine.QuadraticSolver;
 import io.github.mangara.diophantine.Utils;
 import io.github.mangara.diophantine.XYPair;
-import io.github.mangara.diophantine.quadratic.ParabolicSolver;
 import io.github.mangara.diophantine.quadratic.PellsSolver;
 
 public final class NumberTheory {
@@ -6725,13 +6724,6 @@ private static IASTAppendable diophantinePolynomial(
             return result;
           }
         }
-        if (a.signum() != 0 || b.signum() != 0 || c.signum() != 0) {
-          // D := b^2 - 4ac && D == 0
-          BigInteger D = b.multiply(b).subtract(a.multiply(c).multiply(BigInteger.valueOf(4)));
-          if (D.signum() == 0) {
-            diophantineSolver = ParabolicSolver.solve(a, b, c, d, e, f);
-          }
-        }
         if (diophantineSolver == null) {
           diophantineSolver = QuadraticSolver.solve(a, b, c, d, e, f);
         }