anyone good math proofs?

Question

Skullmaster2017 · Answer

@dude @Vocaloid

xXMarcelieXx · Answer

attachment

Skullmaster2017 · Answer

Hero · Answer

Suppose A = {3,4}, B = {4,5}, C = {3,4,5} then what @xXMarcelieXx

xXMarcelieXx · Answer

arent we suppose to negate first?

Hero · Answer

I don't see it necessary to negate anything.

xXMarcelieXx · Answer

oh i thought we would negate when we want to disprove something?

Hero · Answer

Nope. You just have to show that the statement is false.

xXMarcelieXx · Answer

hmmm i have no idea whats next lol

Hero · Answer

Try finding $A \cup C$ and $B \cup C$

xXMarcelieXx · Answer

A u C  and B u C we would get  an empty set ?

xXMarcelieXx · Answer

oh wait no.. sorry i messed up

xXMarcelieXx · Answer

A u  C  = {  3 , 4 , 5 }
  B  u C  = { 3 , 4 , 5 }

Hero · Answer

So what can you conclude so far as it applies to the given statement?

xXMarcelieXx · Answer

that they  are actually the same sets

Hero · Answer

So $A \cup C \subseteq A \cup B$ is true. Now can we then conclude that $A \subseteq B$?

Hero · Answer

Why or why not?

xXMarcelieXx · Answer

so A is " A u  C "  ?
sorry im confused with the notation with A   c/ B

Hero · Answer

$A = \{3,4\}$

$A \cup C = \{3,4,5\}$

Hero · Answer

$A \subseteq B$ means A is either a subset of B or A = B

Hero · Answer

Is that the case here?

xXMarcelieXx · Answer

hmm its not a subset since we dont have the same sets

Hero · Answer

A is not a subset of B because 3 is a member of A, but not a member of B.

Hero · Answer

The End.

Hero · Answer

BTW, it is impossible to do the proof if you're unfamiliar with the related terminology.

xXMarcelieXx · Answer

dang thats all ? LOL 
Ik but i struggle with proof terminology :(

Hero · Answer

Hero · Answer

Best to go through the definitions and organize your own notes on them. Then attempt to do the proofs.