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**dee93****Member**- Registered: 2013-08-12
- Posts: 19

Hi guys can you please help me with this question and explain how i determine which boolean function is in the uploaded circuit?

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Hint: Put all the values of P and Q and evaluate the truth table.

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,020

hi dee93

My picture shows the three logic symbols being used here.

I think I'd work back from the output end, so you get the right brackets.

The last logic gate is an OR so start with

(... OR ...)

The top input to that OR is also an OR and the bottom input is an AND so that makes it

( (...OR...) OR (...AND...))

I'll do one more step for you.

The top input to the OR is from p through a NOT gate so now we have

( (p' OR ...) OR (...AND...) )

See if you can finish it off.

Question. Are you expected to simplify it as well?

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**dee93****Member**- Registered: 2013-08-12
- Posts: 19

bob bundy wrote:

hi dee93

My picture shows the three logic symbols being used here.

I think I'd work back from the output end, so you get the right brackets.

The last logic gate is an OR so start with

(... OR ...)

The top input to that OR is also an OR and the bottom input is an AND so that makes it

( (...OR...) OR (...AND...))

I'll do one more step for you.

The top input to the OR is from p through a NOT gate so now we have

( (p' OR ...) OR (...AND...) )

See if you can finish it off.

Question. Are you expected to simplify it as well?

Bob

its a two part question I have no idea how to write it.

a) What Boolean function is implemented by the circuit

) The screen shot shows that inputs of p=0 and q=0 give an outputof 1. Confirm that your Boolean function from part (a) evaluates to 1when p and q are set to 0.

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,020

That doesn't seem to require any simplification so what I said before should be fine for (a).

In your earlier thread I made some truth tables. You can do this for your function.

eg

( p ' + q ) AND p

0 1 1 0 0 0

Bob

ps. If you post a function first I'll check it for you.

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**dee93****Member**- Registered: 2013-08-12
- Posts: 19

bob bundy wrote:

That doesn't seem to require any simplification so what I said before should be fine for (a).

In your earlier thread I made some truth tables. You can do this for your function.

eg

( p ' + q ) AND p

0 1 1 0 0 0Bob

ps. If you post a function first I'll check it for you.

I have come up with, p (p + q ' ) ?

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,020

How?

The circuit has 6 gates, 4 without the NOTs.

When I partly did the question, I had 4 of the gates done for you.

How have you got it to just 3 gates?

What happened after ( (p' OR ...) OR (...AND...) )

Bob

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**dee93****Member**- Registered: 2013-08-12
- Posts: 19

bob bundy wrote:

How?

The circuit has 6 gates, 4 without the NOTs.

When I partly did the question, I had 4 of the gates done for you.

How have you got it to just 3 gates?

What happened after ( (p' OR ...) OR (...AND...) )

Bob

what exactly do i need to add to it?

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,020

I think you need some easier practice first. I'd be happy to go back a few steps and lead you back to this problem, with some easier ones first.

Would you like to try this?

bob

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**dee93****Member**- Registered: 2013-08-12
- Posts: 19

bob bundy wrote:

I think you need some easier practice first. I'd be happy to go back a few steps and lead you back to this problem, with some easier ones first.

Would you like to try this?

bob

my homework needs to be done lol practice can come latter.I'm more of an IT guy but discrete math comes with my course unfortunately cant wrap my head around math at all.

*Last edited by dee93 (2013-08-15 04:43:20)*

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,020

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Which rule he did not follow?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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