Update app.py

app.py

@@ -242,7 +242,7 @@ elif selected_function == "問題生成":
                 # 例: (x + sqrt(5))*(x - sqrt(2)) = 0
                 a = random.randint(min_value, max_value)
                 b = random.randint(min_value, max_value)
-                init_problem = f"(x + sqrt({abs(a)}))*(x - sqrt({abs(b)})) = 0"
+                init_problem = f"(x + sqrt({abs(a)}))*(x+ sqrt({abs(b)})) = 0"
                 expression = init_problem
                 if expression:
                     result = expand(expression)