Fixed bugs in scipy test and notebook (#185)

Author: ramador09

library_scipy.ipynb

@@ -1288,7 +1288,16 @@
    "source": [
     "### 4.8. Exercise: $LU$ decomposition 🌶️\n",
     "\n",
-    "For matrices $P, L,$ and $U$ defined in [§4.5](#45-matrix-decomposition-decomposition), express the matrix in [Exercise 4.8.](#48-exercise-eigenvalue-problem) as a product of matrices $P, L, U$."
+    "For matrices $P, L,$ and $U$ defined in [§4.5](#45-matrix-decomposition-decomposition), express the following matrix as a product of matrices $P, L, U$.\n",
+    "$$\n",
+    "\\left[\n",
+    "\\begin{array}{ccc}\n",
+    "9 & 3 & 3 \\\\\n",
+    "3 & 2 & 2 \\\\\n",
+    "3 & 4 & 2\n",
+    "\\end{array}\n",
+    "\\right]\n",
+    "$$"
    ]
   },
   {

tutorial/tests/test_library_scipy.py

@@ -5,7 +5,7 @@ def reference_minimize():
     from scipy.optimize import minimize
 
     def f(x):
-        return 3 * x**2 - 4 * x - 4
+        return 3 * x**2 - 5 * x - 4
 
     return minimize(f, 0)
 
@@ -22,7 +22,7 @@ def f(x):
         return x**3 - 6 * x**2 + 4 * x + 12
 
     # 2. TODO: call the root function here:
-    sol1, sol2, sol3 = root(f, -1.0), root(f, 2.5), root(f, 4.5)
+    sol1, sol2, sol3 = root(f, -1.0).x, root(f, 2.5).x, root(f, 4.5).x
     return sol1, sol2, sol3