888 Answered Questions for the topic discrete math

11/29/16

There are 57 students in a class, how many different ways can you make a group of 5?
There are 57 students in a class, how many different ways can you make a group of 5?
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11/24/16

Define functions f, g, h, all of which map from R -> R. (Discrete Mathematics, Functions)
f(x) = -(x - 1)g(x) = 2x2h(x) = 3x + 1 a. What is (f ο g)(-2)?b. What is (g ο f)(-2)?c. What is (f ο h)-1(3)?d. What is (f ο g ο h)(1)?e. What is (h ο h-1)(π)?
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Discrete Math Math Math Help Mathematics

10/25/16

Consider the surjective function cos: R ? [-1, 1] and let ~ be the associated equivalence relation x ~ y ?? cos x = cos y. Find the Equivalence Class
Consider the surjective function cos: R → [−1, 1] and let ∼ be the associated equivalence relationx ∼ y ⇐⇒ cos x = cos y.   Describe the equivalence classes of ∼. (b) Do the analogous exercise... more
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09/29/16

show that R x Zn has an identity element.
Suppose that R is a ring of characteristic n. If addition and multiplication are defined in R x Zn = {(x, a)lx E R; a E Zn} by (x, a) + (y, b) = (x + y, a +n b), (x, a)(y, b) = (xy + ay + bx,... more
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09/29/16

Ideal and subring
please I want help with that     Consider the ring Mn(R) ofn x n matrices over R, a ring with identity. A square matrix (aij) is said to be upper triangular if aij = 0 for i > j and strictly... more
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Discrete Math Math

09/17/16

How to solve the Intersection of the cross product of two sets | (CxD) n (DxC)
I have a set C: {0,1,3)   and set D: {2,8}   I have the product of sets CxD and DxC   So for example CxD: {(0,2) , (0,8),} {(1,2), (1,8),} {(3,2), (3,8)}   And DxC is the opposite... more
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Discrete Math

07/30/16

Exxplaining Induction pt 2
What I am really looking for here is an explanation as to why this process is actually able to prove that a statement is true for all values of n. Try to make your example non-mathematical and... more
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Discrete Math

07/29/16

The Big O Notation
Suppose we are given the following program segment: F(x) = 0Input nFor x = 1 to x = ny = x*(x+3)+2Print yNext x 1. Determine the number of steps the program will execute before entering the loop.2.... more
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Discrete Math

07/28/16

How to Explain Induction to a friend who complete confused?
How would you explain to this person why it is that induction actually does work. In my follow up responses to you, I may ask you questions that your friend might as in response to your... more
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Discrete Math Pigeon Hole

07/13/16

A sack contains 48 marbles of four different colors. Exactly 8 of the marbles are red. Prove that the sack must contain at least 14 marbles which are of the sam
Pigeon hole principle 
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06/13/16

Expected Value + Probability
Twenty distinct integers are arranged in a list in a random order, such that all 20! orderings are equally likely. Going down the list, one marks every number that is larger than all earlier... more
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05/30/16

security codes are made of 3 letters followed by four single digit numbers
security codes are made of 3 letters followed by four single digit numbers. How many different 7 character security codes can be made if none of the letters can repeat and the first digit must be odd? more
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Discrete Math

05/30/16

Repetitive Nearest-Neighbor Algorithm
suppose that in solving a tsp you use the cheapest link algorithm and find a cheapest link tour with a length of 21400 miles. suppose that you later find out that the length of an optimal tour is... more
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05/11/16

Let p be a odd prime, If ord p (a) = h and h is even, then a^(h/2)= -1 mod p
Determine is, in general, true or false. Recall that auniversal statement is true if it is true for all possible cases while it is false if there is even onecounterexample. Be prepared to prove... more
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Discrete Math Math Proof

05/05/16

let m,n belong to N, and m,n>1, prove that mn< (m+n)choose 2
let m,n belong to N, and m,n>1, prove that mn< (m+n)choose 2     Please help. Thank you!  
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05/05/16

let G=(V,E) be a graph and suppose a,b belong to V. Prove that if there is a walk from a to b, then there is a path from a to b
use the well-ordering principle.   Please help with this question, it's a practice problem, I just can't figure out. Thank you!
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05/03/16

Please help me with the proof below!
let 〈xn〉n=1...∞ be a sequence satisfying xn+1=xn-xn-1 for each n.Prove that ∀ n ∈ N, xn+6=xn by induction     Please help me. I'm reviewing for my final and something like this may appear on it.
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05/03/16

Please help with proof by induction below
let 〈xn〉n=1...∞ be a sequence satisfying xn+1=xn-xn-1 for each n. Prove that ∀ n ∈ N, xn+6=xn by induction
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Discrete Math Math Graph Theory

04/26/16

Grap theory question, please help
let G=(V,E) be a graph where V={A⊆N5||A|=2} and E={{A,B}⊆V|A∩B=ø} sketch this graph and find its size
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Discrete Math Proof

04/19/16

Prove that for every natural number n, cos(nx) can be expressed as a polynomial in cos(x) of degree n
please help, Im very confused. This one on my exam and I didnt understand it at all. Want to know the answer so I can study for my final.
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04/19/16

Ten people check their hats in a resturant. The resturant is evacuated quickly. Everyone grabs a hat. In how ma...
Ten people check their hats in a resturant. The resturant is evacuated quickly. Everyone grabs a hat. In how many ways can it happen, that noone gets the right hat? Please help! this is a... more
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04/19/16

Please help with the combinations and Permutations problem below
A club has 30 members under the age of 30 and 40 members who are 30 or older. In how many ways can a slate of officers be chosen if the President and atleast one other officer must be at least 30... more
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Discrete Math Math Proof

04/18/16

Very challenging proof: Prove that for every natural number n, cos(nx) can be expressed as a polynomial in cos(x) of degree n
Please help! I do not know how to do this practice problem. My professor told us to try it for fun. But, he never went over it in class. And now im curious
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04/18/16

Please help with the question below (combinations and permutations)
A club has 30 members under the age of 30 and 40 members who are 30 or older. In how many ways can a slate of officers be chosen if the President and atleast one other officer must be at least 30... more
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Discrete Math

04/17/16

Discrete Math
(Proof by contradiction the following statement)   If a and b are rational numbers, b does not = 0, and r is an irrational number, then a + br is irrational.
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