diff --git a/apps/regression/model/cubic_model.cpp b/apps/regression/model/cubic_model.cpp
index 75705bfbc..4acbd07b2 100644
--- a/apps/regression/model/cubic_model.cpp
+++ b/apps/regression/model/cubic_model.cpp
@@ -38,7 +38,7 @@ ExpressionLayout * CubicModel::layout() {
   return layout;
 }
 
-Expression * CubicModel::expression(double * modelCoefficients) {
+Expression * CubicModel::simplifiedExpression(double * modelCoefficients, Poincare::Context * context) {
   if (m_expression != nullptr) {
     delete m_expression;
     m_expression = nullptr;
@@ -68,6 +68,7 @@ Expression * CubicModel::expression(double * modelCoefficients) {
   Expression * dExpression = new Decimal(d);
   Expression * const operands[] = {ax3Expression, bx2Expression, cxExpression, dExpression};
   m_expression = new Addition(operands, 4, false);
+  Expression::Simplify(&m_expression, *context);
   return m_expression;
 }
 
diff --git a/apps/regression/model/cubic_model.h b/apps/regression/model/cubic_model.h
index 1a5369ec6..2c3359352 100644
--- a/apps/regression/model/cubic_model.h
+++ b/apps/regression/model/cubic_model.h
@@ -10,7 +10,7 @@ class CubicModel : public Model {
 public:
   CubicModel() : m_expression(nullptr) {}
   Poincare::ExpressionLayout * layout() override;
-  Poincare::Expression * expression(double * modelCoefficients) override;
+  Poincare::Expression * simplifiedExpression(double * modelCoefficients, Poincare::Context * context) override;
   I18n::Message formulaMessage() const override { return I18n::Message::CubicRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
diff --git a/apps/regression/model/model.cpp b/apps/regression/model/model.cpp
index a01d216d1..a002728d4 100644
--- a/apps/regression/model/model.cpp
+++ b/apps/regression/model/model.cpp
@@ -12,8 +12,10 @@ using namespace Shared;
 namespace Regression {
 
 double Model::levelSet(double * modelCoefficients, double xMin, double step, double xMax, double y, Poincare::Context * context) {
-  Decimal * yExpression = new Decimal(y);
-  double result = expression(modelCoefficients)->nextIntersection('x', xMin, step, xMax, *context, yExpression).abscissa;
+  Expression * yExpression = static_cast<Expression *>(new Decimal(y));
+  Expression::Simplify(&yExpression, *context);
+  Expression * modelExpression = simplifiedExpression(modelCoefficients, context);
+  double result = modelExpression->nextIntersection('x', xMin, step, xMax, *context, yExpression).abscissa;
   delete yExpression;
   return result;
 }
diff --git a/apps/regression/model/model.h b/apps/regression/model/model.h
index e47cb73ec..71e788d05 100644
--- a/apps/regression/model/model.h
+++ b/apps/regression/model/model.h
@@ -27,7 +27,7 @@ public:
   static constexpr int k_maxNumberOfCoefficients = 5;
   virtual ~Model() = default;
   virtual Poincare::ExpressionLayout * layout() = 0;
-  virtual Poincare::Expression * expression(double * modelCoefficients) { return nullptr; } //TODO keep this so no need to implement for bijective functions?
+  virtual Poincare::Expression * simplifiedExpression(double * modelCoefficients, Poincare::Context * context) { return nullptr; } //TODO keep this so no need to implement for bijective functions?
   virtual I18n::Message formulaMessage() const = 0;
   virtual double evaluate(double * modelCoefficients, double x) const = 0;
   virtual double levelSet(double * modelCoefficients, double xMin, double step, double xMax, double y, Poincare::Context * context);
diff --git a/apps/regression/model/quadratic_model.cpp b/apps/regression/model/quadratic_model.cpp
index bedb367db..6f4989e2e 100644
--- a/apps/regression/model/quadratic_model.cpp
+++ b/apps/regression/model/quadratic_model.cpp
@@ -30,7 +30,7 @@ ExpressionLayout * QuadraticModel::layout() {
   return layout;
 }
 
-Expression * QuadraticModel::expression(double * modelCoefficients) {
+Expression * QuadraticModel::simplifiedExpression(double * modelCoefficients, Poincare::Context * context) {
   if (m_expression != nullptr) {
     delete m_expression;
     m_expression = nullptr;
@@ -52,6 +52,7 @@ Expression * QuadraticModel::expression(double * modelCoefficients) {
   Expression * cExpression = new Decimal(c);
   Expression * const operands[] = {ax2Expression, bxExpression, cExpression};
   m_expression = new Addition(operands, 3, false);
+  Expression::Simplify(&m_expression, *context);
   return m_expression;
 }
 
diff --git a/apps/regression/model/quadratic_model.h b/apps/regression/model/quadratic_model.h
index fa94de678..a6e8ba9b1 100644
--- a/apps/regression/model/quadratic_model.h
+++ b/apps/regression/model/quadratic_model.h
@@ -10,7 +10,7 @@ class QuadraticModel : public Model {
 public:
   QuadraticModel() : m_expression(nullptr) {}
   Poincare::ExpressionLayout * layout() override;
-  Poincare::Expression * expression(double * modelCoefficients) override;
+  Poincare::Expression * simplifiedExpression(double * modelCoefficients, Poincare::Context * context) override;
   I18n::Message formulaMessage() const override { return I18n::Message::QuadraticRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
diff --git a/apps/regression/model/quartic_model.cpp b/apps/regression/model/quartic_model.cpp
index 42c0d4fdb..8d9a81b31 100644
--- a/apps/regression/model/quartic_model.cpp
+++ b/apps/regression/model/quartic_model.cpp
@@ -46,7 +46,7 @@ ExpressionLayout * QuarticModel::layout() {
   return layout;
 }
 
-Expression * QuarticModel::expression(double * modelCoefficients) {
+Expression * QuarticModel::simplifiedExpression(double * modelCoefficients, Poincare::Context * context) {
   if (m_expression != nullptr) {
     delete m_expression;
     m_expression = nullptr;
@@ -84,6 +84,7 @@ Expression * QuarticModel::expression(double * modelCoefficients) {
   Expression * eExpression = new Decimal(e);
   Expression * const operands[] = {ax4Expression, bx3Expression, cx2Expression, dxExpression, eExpression};
   m_expression = new Addition(operands, 5, false);
+  Expression::Simplify(&m_expression, *context);
   return m_expression;
 }
 
diff --git a/apps/regression/model/quartic_model.h b/apps/regression/model/quartic_model.h
index 5a7961ee6..897bbc4ed 100644
--- a/apps/regression/model/quartic_model.h
+++ b/apps/regression/model/quartic_model.h
@@ -10,7 +10,7 @@ class QuarticModel : public Model {
 public:
   QuarticModel() : m_expression(nullptr) {}
   Poincare::ExpressionLayout * layout() override;
-  Poincare::Expression * expression(double * modelCoefficients) override;
+  Poincare::Expression * simplifiedExpression(double * modelCoefficients, Poincare::Context * context) override;
   I18n::Message formulaMessage() const override { return I18n::Message::QuarticRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
diff --git a/apps/regression/model/trigonometric_model.cpp b/apps/regression/model/trigonometric_model.cpp
index 327d4938e..a75241a49 100644
--- a/apps/regression/model/trigonometric_model.cpp
+++ b/apps/regression/model/trigonometric_model.cpp
@@ -30,7 +30,7 @@ ExpressionLayout * TrigonometricModel::layout() {
   return layout;
 }
 
-Expression * TrigonometricModel::expression(double * modelCoefficients) {
+Expression * TrigonometricModel::simplifiedExpression(double * modelCoefficients, Poincare::Context * context) {
   if (m_expression != nullptr) {
     delete m_expression;
     m_expression = nullptr;
@@ -49,6 +49,7 @@ Expression * TrigonometricModel::expression(double * modelCoefficients) {
         false),
       false);
   m_expression = new Multiplication(aExpression, sinExpression, false);
+  Expression::Simplify(&m_expression, *context);
   return m_expression;
 }
 
diff --git a/apps/regression/model/trigonometric_model.h b/apps/regression/model/trigonometric_model.h
index a646fd61b..6c28dc2c5 100644
--- a/apps/regression/model/trigonometric_model.h
+++ b/apps/regression/model/trigonometric_model.h
@@ -10,7 +10,7 @@ class TrigonometricModel : public Model {
 public:
   TrigonometricModel() : m_expression(nullptr) {}
   Poincare::ExpressionLayout * layout() override;
-  Poincare::Expression * expression(double * modelCoefficients) override;
+  Poincare::Expression * simplifiedExpression(double * modelCoefficients, Poincare::Context * context) override;
   I18n::Message formulaMessage() const override { return I18n::Message::TrigonometricRegressionFormula; }
   double evaluate(double * modelCoefficients, double x) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;