Fixed section heading

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07_Kalman_Filter_Math/Kalman_Filter_Math.ipynb

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+     "source": [
+      "Forming First Order Equations from Higher Order Equations"
+     ]
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-      "### Forming First Order Equations from Higher Order Equations\n",
-      "\n",
       "In the sections above I spoke of *first order* differential equations; these are equations with only first derivatives. However, physical systems often require second or higher order equations. Any higher order system of equations can be converted to a first order set of equations by defining extra variables for the first order terms and then solving. Let's do an example. \n",
       "\n",
       "Given the system $\\ddot{x} - 6\\dot{x} + 9x = t$ find the first order equations.\n",