Ok, I am having a difficult time with the following problem. I am to show that the two sides are equal. x1'x3 + x1x2x3' +x1'x2+x1x2' = x2'x3+x1x3'+x2x3'+x1'x2x3 For the LHS I can simplify it to: x2(x1'+x1x3') + x1'x3 + x1x2' x2x1' + x2x3' + x1'x3 + x1x2' x1'x3 + x2x3' + x1x2' For the RHS I can simplify to: x2(x3' + x1'x3) + x2'x3 + x1x3' x2x3' + x2x1' + x2'x3 + x1x3' x1'x3 + x1'x2 + x2x3 At this point I am stuck. I know that both sides should be equal. I have to do this algebraically, so using a truth table is out of it.