9000022904

Find the values of a real parameter $t$ which ensure that the following system has a unique solution. $$\begin{array}{rlrlrlrlrlrlrlr}2x& +& y& +& t& =-& 2& & & & & & & & \\ -4x& -2& y& +& 1& =& 0& & & & & & & & \end{array}$$