You are not logged in.

- Topics: Active | Unanswered

- Index
- » Help Me !
- »
**Help FAST!**

Pages: **1**

**Lolz****Member**- Registered: 2017-07-30
- Posts: 4

Let m be a positive integer, and suppose that 9 is its own inverse (mod m), but 3 is not its own inverse (mod m). How many values for m are there?

Offline

Deduce from the first statement that divides , which gives you a small number of possibilities to test against the second statement. ( of them, to be precise.)

**LearnMathsFree: Videos on various topics.New: Integration Problem | Adding FractionsPopular: Continued Fractions | Metric Spaces | Duality**

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,139

Good morning zetafunc,

Are you assuming the operation is x; as in 9x9 = 81 ?

I had assumed the op is +

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

Hi Bob,

I was assuming that they meant the multiplicative inverse, yes -- if they meant additive inverse, the problem is very similar (though produces a different answer).

**LearnMathsFree: Videos on various topics.New: Integration Problem | Adding FractionsPopular: Continued Fractions | Metric Spaces | Duality**

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,139

hi

For + I'm getting two values; m=9 and m=18

What do you think?

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

Yes, I agree with that.

**LearnMathsFree: Videos on various topics.New: Integration Problem | Adding FractionsPopular: Continued Fractions | Metric Spaces | Duality**

Offline

Pages: **1**

- Index
- » Help Me !
- »
**Help FAST!**