# Math Is Fun Forum

Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #1 Re: Help Me ! » FOR BOB: Equitable Mathematics » 2024-05-27 06:46:01

mathxyz wrote:

I have deleted the posts in this thread as you have broken our rules by making  a personal attack on another member.

I have also removed your signature as I find it equally offensive  Any further infringements and you will be banned. Bob

Are you saying that supporting Trump is offensive? In what way is it offensive?

## #2 Re: Help Me ! » FOR BOB: Equitable Mathematics » 2024-05-27 06:44:55

Are you saying that it is offensive to support Trump?

## #3 Re: Help Me ! » Exponential Equation » 2024-05-27 06:43:20

Bob wrote:

Correct

Bob

Beautiful. There's nothing more relaxing for me than to stay home resting on days off. I work out math problems and arrange hymns for classical guitar in the early evening hours. I used to go out on days off. Honestly, the city is just too dangerous to enjoy the park, beach, theatre,  etc. I am not exaggerating, Bob. NYC is out of control under democratic leadership.

## #4 Help Me ! » Square Root Prove » 2024-05-27 06:38:58

mathxyz
Replies: 1

Give an example to show that sqrt{a^2} is not equal to a. Use it to explain  why sqrt{a^2} = | a |.

## #5 Re: Help Me ! » Rationalize Denominator » 2024-05-27 06:35:39

Phrzby Phil wrote:

So, what did you get and what does the book say?

## #6 Help Me ! » Simplify Expression » 2024-05-27 06:33:29

mathxyz
Replies: 0

Simplify the expression. Express your answer so that only positive exponents occur. Assume that the variables are positive.

[(16x^2 • y^(-1/3)]^(3/4) divided by [(xy^2)]^(1/4)

After more than 30 minutes with this problem, my answer continues to be (8x^(1/2))/[y^(3/4)].

(8x^(5/4))/[y^(3/4)]

## #7 Re: Help Me ! » Factorial of Decimal Number » 2024-05-27 02:52:11

Bob wrote:

Factorial is only defined for whole numbers.  There is a thing called the gamma function.  See what wolfram says.

Bob

Ok. Thanks.

Here is what the AI app tells me:

Unfortunately, you can't calculate the factorial of a decimal number like 2.5. Here's why:

* **What's a factorial?**  The factorial (represented by the symbol "!") means multiplying a whole number by all the whole numbers less than it down to 1. For example: 5! = 5 * 4 * 3 * 2 * 1 = 120

* **Why not decimals?** Factorials are defined based on the concept of counting and arranging whole objects. You can't have 2.5 objects to arrange, which is why the factorial of a decimal number isn't defined.

## #8 Re: Help Me ! » Bedroom Tiles » 2024-05-27 02:49:40

Bob wrote:

As both 5 and 8 go into both length and width you can put the tiles either way round and there's no half tiles needed.

Quickest is to use n times area of tile = area of floor.

Bob

Copy. Will do.

## #9 Re: Help Me ! » Profit Equation » 2024-05-27 02:44:41

Bob wrote:

A shopkeeper buys an item for C it sells it for R.

Their profit is the difference.

Bob

Can you give me a real life example using money? Sorry for the dumb question but I really want to understand this stuff.

## #10 Re: Help Me ! » Exponential Equation » 2024-05-27 02:43:08

Bob wrote:

You can rewrite this as 2 times 2^(2x)
and use logs

Bob

Copy. Will do.

Bob wrote:

Wolfram agrees.

Bob

Beautiful.

Bob wrote:

Yes.

Bob

## #13 Re: Help Me ! » Rationalize Denominator » 2024-05-27 02:34:52

Bob wrote:

Yes; do it twice so the denominator = 2

Bob

I did that but my answer is not the book's answer. Can you work it out for me?

## #14 Re: Help Me ! » Exponential Equation » 2024-05-27 02:33:35

Bob wrote:

The inconsistency shows I've performed an illegal act so that suggests I cannot cancel as that's really division by zero. That leads to the possibility that x=0. Then check it fits. Anything^0 =1 so LHS = RHS = 0. It works.

Bob

Copy. Moving on....

## #15 Re: Help Me ! » Number Raised To Itself » 2024-05-27 02:32:35

Bob wrote:

Have to. I'd start by using logs

Bob

Using longs? How?

## #16 Help Me ! » Factorial of Decimal Number » 2024-05-26 19:11:42

mathxyz
Replies: 2

I know that, for example, 3! = 3 x 2 x 1 or 6.
What happens when we take the factorial of a decimal number?

Show how to compute the value of (2.5)!

## #17 Help Me ! » Bedroom Tiles » 2024-05-26 19:07:33

mathxyz
Replies: 2

How many tiles of length 5 cm and breadth 8 cm are needed to tile the floor of a bed room 200 cm long and 400 cm wide?

Seeking the set up only.

Thanks.

## #18 Help Me ! » Exponential Equation » 2024-05-26 19:04:08

mathxyz
Replies: 2

Find x.

2^(2)^(2)^(2) = 4^(x)

Let me see.

2^[(2)^(2)] = 2^(4) = 16.

I now have 2^(16) = 4^(x).

Let 4^(x) = 2^(2)

2^(16) = 2^(2x)

Same base on both sides means to equate powers.

16 = 2x

16/2 = x

8 = x

You say?

## #19 Help Me ! » Profit Equation » 2024-05-26 18:58:56

mathxyz
Replies: 2

The profit equation is given as

P = R - C, where P is profit, R is revenue and C is cost.

Can someone explain what the profit equation actually means and how to use it by providing a real life word problem?

## #20 Help Me ! » Exponential Equation » 2024-05-26 18:52:54

mathxyz
Replies: 2

Find x.

4^(x) + 4^(x) = 1

How is this done?

P. S. I continue my self-study of college algebra with Sullivan on paper and will post from the book when I get stuck.

## #21 Help Me ! » 6^6^6 Divided By 10 » 2024-05-26 18:48:16

mathxyz
Replies: 2

What is 6^(6)^(6) ÷ 10?

Let me see.

Note: 6^(6) = 46656.

I now have 6^(46656) ÷ 10.

Using a calculator,  I get this:

6^(46656) = 2.65911977215 x 10^(36305).

[2.65911977215 x 10^(36305)]/10

I get 2.65911977215 x 10^(36304).

You say?

## #22 Help Me ! » Find Three Numbers » 2024-05-26 18:41:24

mathxyz
Replies: 2

The product of three consecutive positive odd integers divided by their sum is equal to 95.  What are these three numbers?

Let n, n + 2, and n + 4 be the three consecutive odd integers.

Let me see.

[(n(n + 2)(n + 4)]/[n + n + 2 + n + 4] = 95

Is this the correct set up?

## #23 Re: Help Me ! » Rationalize Denominator » 2024-05-26 18:37:40

Phrzby Phil wrote:

What do you need to multiple the denominator by so that it is an integer?  Multiple the numerator by the same.

I will write cuberoot(2) as 2^(1/3).

Do you mean to multiply the top and bottom by 2^(1/3)?

## #24 Re: Help Me ! » Seeking Formula » 2024-05-26 18:35:44

Bob wrote:

If 1 is the zero row and 1  1 the first row and 1  2  1 the second row then the formula is

where n is the row number and r the (r+1) th element.

So put n=20 and r = 6

Bob

If you ask me nicely on Wednesday I'll show you the proof (by induction).

Ok. Looks easy to do. Thanks.

## #25 Re: Help Me ! » More Prime Numbers » 2024-05-26 18:31:38

Bob wrote:

You know that list I told you to keep. Well it's easy to just check. Or start with the squares and add 8.

Bob

I guess there's no getting away from making a list.