2 sides 2, 3: 3rd side can't be? / set closure / equiv. stmt

[danielleee]

two sides of a triangle are 2 and 3. the third side can not be...

(a) 1 (b) 2 (c) 3 (d)4

Which set is NOT closed under addition?
1. natural numbers
2. even integers
3. whole numbers
4. odd integers

Which statement is logically equivalent to the statement "If x=3, then x is a prime number"?
1. if x is a prime numbers, then x=3
2. if x is not equal to 3, then x is not a prime number
3. if x is a prime number, then x is not equal to 3
4.if x is not a prime number, then x=3

thank you ! <3

 

[Deleted member 4993]

Re: triangle sides!

two sides of a triangle are 2 and 3. the third side can not be...

(a) 1 (b) 2 (c) 3 (d)4

Triangle inequality : Sum of any two sides of a triangle is greater than the third side.


Which set is NOT closed under addition?
1. natural numbers
2. even integers
3. whole numbers
4. odd integers

What does "closed under addition" mean?

Which statement is logically equivalent to the statement "If x=3, then x is a prime number"?
1. if x is a prime numbers, then x=3
2. if x is not equal to 3, then x is not a prime number
3. if x is a prime number, then x is not equal to 3
4.if x is not a prime number, then x=3

Make sure you have posted the statements correctly

thank you ! <3

 

[danielleee]

Re: triangle sides!

woops, on the third question - the third choice is supposed to be if x is not a prime number than x is not equal to 3 ; i'm pretty sure that's the right answer?

for the second question..idk what closed means

and is the answer to the first one, 1?

 

[Deleted member 4993]

Re: triangle sides!

woops, on the third question - the third choice is supposed to be if x is not a prime number then x is not equal to 3 ; i'm pretty sure that's the right answer? <<< Correct - that is the contra-positive statement

for the second question..idk what closed means <<<TLUIYTB (Then look up in your text book) - or use google and tell us what did you find,

and is the answer to the first one, 1? <<< Correct - but why?

 

[danielleee]

Re: triangle sides!

A set of elements is closed under an operation if, when you apply the
operation to elements of the set, you always get another element of
the set. ....so the answer would be whole numbers?


and because 2+1 isnt greater than 3

 

[Deleted member 4993]

Re: triangle sides!

A set of elements is closed under an operation if, when you apply the
operation to elements of the set, you always get another element of
the set. ....so the answer would be whole numbers?<<< No...

If you add two whole numbers - you would get another whole number. Then set of all the numbers is closed under addition.

and because 2+1 isnt greater than 3<<<Correct