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1. ### Prove that none of them is prime

i don't know, I am confused!
2. ### Prove that none of them is prime

you would start at n! + 1,000,003 ?
3. ### Prove that none of them is prime

So there are n-2 consecutive non-primes starting with n! ?
4. ### Prove that none of them is prime

ok, so a factor of n!+3 is 3, and a factor of n!+2 is 2 and so on. So a factor of n!+n is n. This shows that none of them is prime. How would i go about doing the second part of the question?
5. ### Prove that none of them is prime

Is (n factorial + 2) a factor of it? Which would then apply to the others, which would show that none of them were prime. For them each to be prime, their only factors would have to be themselves and 1.
6. ### Prove that none of them is prime

Homework Statement Let n be a part of the natural numbers, with n>=2. Consider the numbers [n factorial +2 ], [n factorial + 3], ..., [n factorial + n]. Prove that none of them is prime, and deduce that there are arbitrarily long finite stretches of consecutive non-prime nummbers in the...
7. ### Fermat's little theorem

This is ok if p doesn't divide n, but the question asks me for all integers n. So how do i show it's also true for when p divides n?
8. ### Fermat's little theorem

sorry, silly mistake. dividing by n would give me, n^(p-1) equivalent to 1 (mod p) which is fermat's little theorem. so is this all i need to do?
9. ### Fermat's little theorem

ok, so in my question, c=n ? So by dividing by n i would get, 1^p is equiavlent to 1 (mod p) How do i reach n^(p-1) on the left hand side?
10. ### Fermat's little theorem

Homework Statement From fermat's little theorem deduce that when p is prime, n^p is equivalent to n (mod p) for all integers n. Homework Equations The Attempt at a Solution I know from Fermat's Little Theorem that , n^(p-1) is equivalent to 1 (mod p), but i don't...
11. ### L'hopitals rule?

yea, thank you!
12. ### L'hopitals rule?

Homework Statement Find the limit of f(x)=[xcosx]/[x^3 + 1] as x tends to infinity. Homework Equations The Attempt at a Solution Can i use l'hopitals rule here? Or if not, what are the conditions for f(x) to meet so that i may use l'hopitals rule? Without using l'hop i know...
13. ### Converging series

Homework Statement Show that the following series converges: Homework Equations Sum of (from n=1 to infinity) of [3^n + 4^n] / [3^n + 5^n] The Attempt at a Solution Some help on this question would be much appreciated as i really don't know how to start it. Thanks
14. ### Complex Integration

Homework Statement Evaluate the following intergral: Homework Equations Intergral from gamma of (y)dz, where gamma is the union of the line segments joining 0 to i and then i to i+2 The Attempt at a Solution I have no idea how to do this!
15. ### Identifying if A is Open or Closed

Homework Statement For the following set, state and justify whether or not it is open or closed. Homework Equations A={z| I am z >1} The Attempt at a Solution I know the definition of an open set, but I am not sure how to use it to solve this question.
16. ### Derivative of function

Homework Statement Compute the derivative of the following function. Homework Equations f:[1,-1] arrow [-pie/2, pie/2] given by f(x)=sin^-1 (x) The Attempt at a Solution I know that f ' (x)=1/[sqrt(1-x^2)] Im not sure how to include the intervals of pie given, not sure what...
17. ### Discussing continuity of a function

Homework Statement Discuss the continuity of the function f defined for all x belongs to [0,1] by f(x)=x if x is rational and f(x)=x^2 is x is irrational. Homework Equations The Attempt at a Solution I have no idea how to begin this question...some help would be great thanks!
18. ### Limit, as x tends to 0

Homework Statement Does f(x) tend to a limit as x tends to 0? Homework Equations f(x)=[sinx]/[x^2] The Attempt at a Solution Well i sinx would tend to zero and so would x^2, so would the limit just be zero?
19. ### Converging series

i know for the comparison test, you assume that a(n)<= k.b(n) Then if b(n) is convergent, a(n) is also convergent. However i still don't see how i can get my series to be <= to a constant times another series.
20. ### Converging series

Homework Statement Show that the following series converges: Homework Equations Sum of n=1 to n=infinity of [(n+1)/(n^2 +1)]^2 The Attempt at a Solution I thought about using the ratio test, so if the limit as n tends to infinity of a(n+1) / a(n) < 1, then a(n) - the series - would...
21. ### Sequence infinity proof

Homework Statement Prove that the following sequence (a(n)) has the property that a(n) tends to infinity as n tends to infinity. Homework Equations a(n)=[n+7]/[2+sin(n)] The Attempt at a Solution i tried l'hopitals rule, so i got 1/cos(n)...which wouldn't work. so I am not...
22. ### Runge-kutta formula

How do i find what k(1) - k(4) is? Do i substitute anything in for h? Also what are the value for t(i) and y(i)?
23. ### Runge-kutta formula

thankyou very much for that...i understand all of what you have said. So i found for my equation that f[t(0),y(0)] = 1, since y'=y and y(0)=1 Im still slightly confused as to how to find y(h)?
24. ### Runge-kutta formula

Homework Statement Use the fourth order Runge-Kutta formula to advance the differential equation: dy/dt = y with y(0)=1 forward one step h. That is find y(h). Homework Equations The Attempt at a Solution The Runge-Kutta formula is: x(i+1)=x(i)+h/6 [k(1)+2k(2)+2k(3)+k(4)]...
25. ### Supremums and infimums

Homework Statement Show that for all x,y in R (real numbers), sup{x,y}=1/2(x+Y+|X-Y|), and inf{x,y}=1/2(X+Y-|x-y|) Homework Equations The Attempt at a Solution i know that the supremum is the lowest upper bound and that the infimum is the largest lower bound. However i really...
26. ### Proof by induction

thanks for the help!
27. ### Proof by induction

Homework Statement Define the numbers a(0),a(1),a(2),...by a(0)=1, a(1)=3, a(n)=4[a(n-1) - a(n-2)]. for n>=2 Show by induction that for all n>=1, a(n)=2^(n-1) [n+2] Homework Equations The Attempt at a Solution proof by induction is not my stong point, and i really don't know where to...
28. ### Proof by induction

Homework Statement Show that (n+1)^4 < 4n^4 whenever n >= 3 Homework Equations The Attempt at a Solution I need to prove this by induction, so i assume it is true and then prove that when n=n+1 it is also true. so it would become (n+2)^4 < 4(n+1)^4 Im not sure how to...
29. ### Supremums 'alpha' and 'beta' problem

Well the definition of supremum is that it's the least upper bound, it is greater than or equal to each element in the set. I still don't know how so start off showing that alpha+beta is the sup of A+B...
30. ### Supremums 'alpha' and 'beta' problem

Homework Statement Let A, B,be two non empty sets of real numbers with supremums 'alpha' and 'beta' respectively, and let the sets A+B and AB be defined by: A+B={a+b / a belongs to A, b belongs to B}, AB= {ab / a belongs to A, b belongs to B}. Show that alpha+beta is a supremum of A+B...
31. ### Rolle's Theorem differentiation

Is the limit when h tends to 0?...then it would be f(d)-f(d)/h, so f '(d) would equal zero. Im not sure what f(d+h) implies though...
32. ### Rolle's Theorem differentiation

c,d do belong to [a,b] so f(a)<f(d), but f(b)>f(d) I don't see how this helps me to show that f ' (d) = 0 thought.
33. ### Increasing functions

Homework Statement Let f : R(real numbers) (arrow) (0,infinity) have the property that f ' (x) = f (x) for all x. Show that f is an increasing functions for all x. Homework Equations The Attempt at a Solution I know that if f ' (x) > 0 , where all of x belongs to a,b (not...
34. ### L'hopital's Rule for solving limit problem

But to use l'hopital's rule, don't you need the limit, x, tending to zero?
35. ### L'hopital's Rule for solving limit problem

The question is: Evaluate the following limit: lim(as x tends to 1) of [(x-1)^3]/(logx) I tried using L'hopital's Rule, so i differentiated the top and bottom of the eqn and i got 3x(x-1)^2, then as x tends to 1 this would tend to 0. I don't think this is correct though, and was wondering...
36. ### What does converse mean?

I had to deduce that sqrt 2 + sqrt 3 was irrational. The question then asks me is the converse true. I am not sure what this means though.
37. ### Proof - irrational numbers

so i let x= a/b then obviously x^2 = a^2/b^2 im not sure how to continue to reach the contradiction
38. ### Proof - irrational numbers

Homework Statement Prove that if x^2 is irrational then x must be irrational. Homework Equations The Attempt at a Solution Maybe do proof by contradiction. I'm not really sure where to start.