too long math bug

[Steven-AA]

missing the end when the math is too long
when I insert this
\[T(n)=\left\{\begin{matrix}\Theta(n^{log_ba})& a> b^k \\\Theta(n^klog\ n)&a=b^k\\\Theta(n^k)&a<b^k\end{matrix}\right.\]
it works well
however, if i click this line , it becomes this
\[T(n)=\left\{\begin{matrix}\Theta(n^{log_ba})& a> b^k \\\Theta(n^klog\ n)&a =b^k\\\Theta(n^k)&a