deletions | additions       diff --git a/Or_frac_vec_x_t__.tex b/Or_frac_vec_x_t__.tex  index e1d9f69..90601b0 100644  --- a/Or_frac_vec_x_t__.tex  +++ b/Or_frac_vec_x_t__.tex 
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Or  $$ \frac{\vec{x}(t+2\Delta t) - \vec{x}(t)}{2 \Delta t} - \frac{\vec{x}(t+\Delta t) - \vec{x}(t-\Delta t)}{2 \Delta t} = \frac{\vec{a}(t) + \vec{a}(t + \Delta t)}{2} \Delta t $$ $$ (\vec{x}(t+2\Delta t) - \vec{x}(t)) - (\vec{x}(t+\Delta t) - \vec{x}(t-\Delta t)) = (\vec{a}(t) + \vec{a}(t + \Delta t)) \Delta t^2 $$