# prooving

The following are equivalent in boolean algebra. 1) a+b=b 2) a*b=a 3) a'+b=1 4) a*b'=0 a)Proove the equivalence of (1) and (2). b)Proove the equivalence of (1) and (3).
2. ### Prooving Factors

How would I prove that 4 is a factor of 6a x 10b ?
3. ### Similar Triangle Prooving

Please see the picture to see the question many Thanks
4. ### prooving monotonicity mmn 11

a1=1 a_n+1=a_n*1/2 how to prove that a_n+1 -a_n<0 ? i tried by induction a1>0 suppose a_n>0 a_n+1 -a_n>0 -a_n*1/2<0 so its monotonicly desendant correct?
5. ### prooving set identities

This is an example solution I am reading but I can't understand the 3rd transformation. (A-B) \cup(B-A) =(A \cup B) - (A \cap B) I understand changing the LHS to (A-B) \cup(B-A) = (A\bigcap B)\cup(B\cap A') < ---a (this) using set diff representation (The notes I am reading use this...
6. ### Prooving trig question

am trying to prove the this trig question but i have been unsucessful. Tan A+ Cot A = 2Cosec 2A
7. ### Role of Rule in Prooving a Function? Help!

Role of Rule in Proving a Function? Help! Problem: Define h: Z \rightarrow Z by the rule h(n) = 4n-1 for all n \in Z Is h onto? Solution: I know that h is not onto because if we suppose 4n-1 = m \in Z then we have to search an n \in Z such that h(n) = m, and for m=0 \in Z there doesn't...
8. ### Graph Theory with Prooving

Let F be a Simple Graph with n >=2 vertices. Proove that F contains at least two vertices of the same degree. well i know that A graph is called simple if there is at most one edge between any two points.
9. ### Prooving

Prooving Primes Let p be the smallest prime dividing a positive integer n with n > p. Prove n is the product of two primes if p^3 > n.
10. ### Prooving inequalities

I'm supposed to proove the proposition that for all integers k>=2, that k^2<k^3. The book says you can use induction or another method. I can't seem to get either fully proved. Any help would be great. Thanks!!
11. ### Prooving 1-1 Function

The function f : Z (INTEGERS) -> N(NATURAL NUMBER) U {0} is defined by f(n) = (2n) if n >= 0, −(2n + 1) if n < 0. Prove f is a bijection. I know its simple, but i need to show it by using lots of math and little english
12. ### Prooving Un/Countable

I'm asked to determine if certain sets are countable or not countable. For the countable sets, I am to exhibit a one-to-one correspondence between the set of natural numbers and that set. One of the sets is: (A) The real numbers with decimal representations of all 1s or 9s I said this is...
13. ### Prooving surjective and injective functions

Let g : A -> B and f : B -> C be functions. Show that if f and g are injective, then f o g is injective. Show that if f and g are surjective, then f o g is surjective. i don't know how to proove it

Show that these statement about real number x are equivalent (i) x is rational (ii) x/2 is rational (iii) 3x-1 is rational. What method that can be used to prove that?
15. ### Prooving and Identity

Hi, I'm struggling to understand how to prove this: (sin^4) T = ( 3 - 4 cos 2 T + cos 4 T ) / 8 (where T is theta) I start on the left side and "break" this up into a square: ( sin^2 T) ^ 2 From here, my book does the following: ( 1 - cos 2 T / 2 ) ^ 2 Why? I know sin^2 is also = 1 -...
16. ### collinear line prooving

The side BC of triangle ABC is produced to D, and E and F lie on CA and AB respectively, such that D, E and F are collinear. Prove that (AF/FB).(BD/DC).(CE/EA)=1 Thanks
17. ### limit prooving question..

the question and where i got stuck in this link: http://img187.imageshack.us/img187/8868/44429492ix7.gif
18. ### Prooving that normal CDF has no closed-form expression

Could somebody recommend a book or an online resource where I could read up on the proof that normal CDF has no close-form expression?
19. ### Teach me the best way of simplyfying this Long Demoivre's Trig Prooving question.

Hi there,i've attached the question in the image...It's basically some test question that takes my time, just being curious can one simplify my technique? thank you very much.
20. ### prooving numbers can be written a certain way

does anyone have advice for working with problems involving numbers that can be written as a specific function of integers i.e. n^3+2n, where n is an integer I want to be able to see which operations will yield results that also may be expressed in this fashion but algebraic manipulation...