Math Is Fun Forum

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Irrational Numbers a and b

Give an example of irrational numbers a and b such that the indicated expression is (a) rational and (b) irrational.

1. a + b

2. a•b

3. a/b

4. a - b

What exactly is this 4 part problem asking for?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,803

Re: Irrational Numbers a and b

These are easier than you think. Make a rational answer

Eg root2/root2 is rational

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Re: Irrational Numbers a and b

These are easier than you think. Make a rational answer

Eg root2/root2 is rational

Bob

Sounds good. Thanks again. I will return later with my work. Going to a job interview now.

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Re: Irrational Numbers a and b

These are easier than you think. Make a rational answer

Eg root2/root2 is rational

Bob

I will a sample of each.

1. a + b

How about sqrt{2} + 3?

2. a•b

How about pi(9)?

3. a/b

How about e/5?

4. a - b

How about sqrt{5} - 1?

You say?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,803

Re: Irrational Numbers a and b

Both a and b are supposed to be irrational.

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Re: Irrational Numbers a and b

Both a and b are supposed to be irrational.

Bob

You are right. Let me try again.

I will a sample of each.

1. a + b

How about sqrt{2} + sqrt{3}?

2. a•b

How about pi times e.

3. a/b

How about e/pi?

4. a - b

How about sqrt{5} - sqrt3}?

You say?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,803

Re: Irrational Numbers a and b

Those will do for examples giving an irrational answer.

Now can do find examples where the answer is rational

Bob

Ps did I read in a post that I now cannot find that you have got a job.  That's great!

---

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Re: Irrational Numbers a and b

Those will do for examples giving an irrational answer.

Now can do find examples where the answer is rational

Bob

Ps did I read in a post that I now cannot find that you have got a job.  That's great!

I need to work on this one some more.