NIMCET 2013 Question Paper with solutions

As we known a tautology is a Boolean formula that is always true. From the giving options, we solve all through the truth table
Here, $\mathit{x}+\stackrel{-}{\mathit{y}}+\stackrel{-}{\mathit{x}}$ is satisfying the condition of tautology.

x	y	$\stackrel{-}{\mathit{x}}$	$\stackrel{-}{\mathit{y}}$	$\mathit{x}+\stackrel{-}{\mathit{y}}+\stackrel{-}{\mathit{x}}$
0	0	1	1	1
0	1	1	0	1
1	0	0	1	1
1	1	0	0	1

The output of $\mathit{x}+\stackrel{-}{\mathit{y}}+\stackrel{-}{\mathit{x}}$ is true