[Math] How to simplify the Boolean function $A’B’C + A’BC’ + ABC + AB’C’$

boolean-algebra

So the question I have asks to implement the circuit with $XOR$ gates.

So I am 3/4 through the problem when I am having problems simplifying the Boolean expressions below:

$$A'B'C + A'BC' + ABC + AB'C'$$

According to the professor this can be simplified to $A \,\,XOR \,\,B\,\, XOR \,\,C$.

The next one: $$A'B'C'D + A'B'CD' + A'BC'D' + A'BCD + ABC'D + ABCD' + AB'C'D' + AB'CD $$

Can be simplified to: $A\,\,XOR \,\,B \,\,XOR\,\,C \,\,XOR\,\,D $.
Again I have no idea how to simplify it to that.

I have not the slightest clue how to even get to that. I have tried many MANY methods I must be looking at this the wrong way. Can anyone help?

Best Answer

$$A′B′C+A′BC′+ABC+AB′C′$$ $$=A^{'}(B^{'}C + BC^{'}) + A(BC + B^{'}C^{'})$$

Now

$X \oplus Y = XY^{'} + X^{'}Y$

$(X \oplus Y)^{'}= XY + X^{'}Y^{'}$

Thus

$$=A^{'}(B \oplus C) + A(B \oplus C)^{'}$$ $$=A \oplus B \oplus C$$

Note that $(\oplus)^{'}$ is the logical expression XNOR

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