00:01
We are given boolean functions and we're asked to find the sum of product expansions of these boolean functions.
00:10
In part a, we're given the function f of x, y, z equals x plus y plus c.
00:29
Determine the sum of products expansion of f, you can either use boolean identities or construct a table that determines all value of f.
00:39
This would be a pretty large table.
00:43
Instead, i'm just going to use boolean identities.
00:46
So first of all, x plus y plus z, by the identity laws, is the same as x times 1 plus y times 1 plus z times 1.
01:00
And this, again, by the identity laws, is equal to x times 1 plus y times 1 times 1 plus z times 1, plus z times 1.
01:15
Off parentheses because of associativity.
01:25
And then using the unit property of boolean variables, this is equal to x times y plus y bar times z plus z bar.
01:53
Now to do a similar thing with the other two terms.
01:56
So plus y times x plus x bar times z plus z bar.
02:02
And plus z times x plus x bar times y plus y bar next i'll use the distributive property for boolean variables so this is xy plus xy bar times z plus z bar plus y x plus y x plus yx plus y x bar times z plus z plus z bar plus x x plus x x bar times y plus y plus y bar then i'll use the distributive law again for these three terms and i get x y z plus x y bar z technically i'm using the distributive law twice here but i'm going to skip some steps to get faster plus x y z bar plus x y bar plus xy bar z bar plus y x z plus y x plus y x bar z plus y x bar plus y x bar plus x bar y plus x bar y bar.
04:13
Next i'll use the commutative law for multiplication.
04:19
And so we get all of our terms x, y, z plus x, y, bar, z, plus x, y, bar, z, plus x, y, z, plus x, y, z again, plus x bar y z, plus x bar, plus x bar, y, z, plus x, y, z bar, plus x, x bar y z bar plus x y z plus x bar y z plus x bar y z plus x y bar z plus x bar y bar z plus x bar y bar z and finally i will use the idempotent law for fully in algebras so we have x plus x times y times z plus x times y times z is x times y times z adding another x to my time z is still x times y times z then we add the x y bar z we add these with the other x y bar z we still have x y bar z then we have our x y z bar we add this with the other x y z bar we still have x y b bar then we have x y bar z bar then we have x y bar z bar adding this with the other x y bar z bar we still have x y bar z bar we still have x y bar z bar adding this the other one, we still have x bar y z.
06:15
Then we have x bar y z bar, and this appears to be the only one of this kind.
06:35
And then we have x bar y bar z.
06:51
And so this is the sum of product formula for part a.
06:59
Okay, in part b, we are given the boolean function f of x y z equals x plus z times y, again, to determine the sum of product expansion of this function, you could use boolean identities or construct a table that determines all values of the function.
07:34
However, constructing the table would take quite a bit of effort, and i don't think it would be particularly enlightening about this function.
07:43
So instead, let's use boolean identities.
07:49
So first, i'll use the distributive law.
07:53
This is xy plus zy.
08:00
Then i'll use the identity law.
08:02
This gives us xy times 1 plus zy times 1...