diff --git a/13-Smoothing.ipynb b/13-Smoothing.ipynb
index b3b5d3f..41875a3 100644
--- a/13-Smoothing.ipynb
+++ b/13-Smoothing.ipynb
@@ -456,9 +456,9 @@
     "    Update Step\n",
     "    \n",
     "$$\\begin{aligned}\n",
-    "\\mathbf{K}_k &= \\mathbf{P}_k\\mathbf{F}^\\mathsf{T} \\hspace{2 mm}\\mathbf{P}^{-1} \\\\\n",
-    "\\mathbf{x}_k &= \\mathbf{x}_k + \\mathbf{K}_k(\\mathbf{x}_{x+1} - \\mathbf{FX}_k) \\\\\n",
-    "\\mathbf{P}_k &= \\mathbf{P}_k + \\mathbf{K}_k(\\mathbf{P}_{K+1} - \\mathbf{P})\\mathbf{K}_k^\\mathsf{T}\n",
+    "\\mathbf{K}_k &= \\mathbf{P}_k\\mathbf{F}^\\mathsf{T}\\mathbf{P}^{-1} \\\\\n",
+    "\\mathbf{x}_k &= \\mathbf{x}_k + \\mathbf{K}_k(\\mathbf{x}_{k+1} - \\mathbf{Fx}_k) \\\\\n",
+    "\\mathbf{P}_k &= \\mathbf{P}_k + \\mathbf{K}_k(\\mathbf{P}_{k+1} - \\mathbf{P})\\mathbf{K}_k^\\mathsf{T}\n",
     "\\end{aligned}$$\n",
     "\n",
     "As always, the hardest part of the implementation is correctly accounting for the subscripts. A basic implementation without comments or error checking would be:\n",