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

You are not logged in.

- Topics: Active | Unanswered

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

Hi guys I am really stuck on this question any clues?

what is the area if the side has a length of x-9

A x^2 -18x +81

B x^6 -15x +34

C x^7 -33x +66

D x^5 -14x +51

E x^3 -28x +27

F x^2 -4x +88

Ok so I know that square area = S² (s= length of side)

So Ill get (x-9)² So what do I do next ?

x² - 81 is what I get and it is none of the above

One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

Hi;

You are not expanding that right:

Want to go over it step by step?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

where did u get the 18 from ?

Yes please

One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

Hi;

Did they ever teach you FOIL?

Or I will teach you my way.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

ooooh yeah I remember that from my algebra course

One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

Okay, let's take a refresher:

F stands for first of each:

O stands for outer of each.

I stands for?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

inner -9 * x

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

Correct!

L is what?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

last -9*-9

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

That is correct and what does (-9) * (-9) equal?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

81

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

Now you add up F,O, I and L and what do you get?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

x²+-9x+-9x+81=

-9x+-9x= -18

x²-18+81

taraaaaaaaaa thank you

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 100,366

Hi zee-f;

That is not quite correct, please check it.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **Thinking is cheating.**

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

oooh I forgot the x

x²-18x+81

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,444

Yes, that's it. Well done!

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

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

Hi really stuck on these questions I did 3 left with 2 :

I have a pizza. The radius is 10 inches long. The pizza was cut into 16 equal slices. When 1 slice was left, my sister and I both wanted it, so we agreed to cut it in half, but I like the crust more than she does, so we decided to cut it the "other way." In other words, the two pieces would not be symmetrical. The inside piece would contain all topping, and the outer piece would contain some topping and some crust.

1. Find the area of the whole pizza. PI * r² = 100PI

2. What is the area of one piece of pizza? (10/360)[(PI)10^2] = 25/9 PI

3. What is the area of a half-piece?(5/360)[(PI)10^2] = 25/18 PI

4. What would the area of the whole pizza be if it were made of half pieces?

5. What is the radius of a half-piece? (ie, where do I need to cut to make two equal halves out of a piece?)

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,444

hi zee-f

I have a pizza. The radius is 10 inches long. The pizza was cut into 16 equal slices. When 1 slice was left, my sister and I both wanted it, so we agreed to cut it in half, but I like the crust more than she does, so we decided to cut it the "other way." In other words, the two pieces would not be symmetrical. The inside piece would contain all topping, and the outer piece would contain some topping and some crust.

1. Find the area of the whole pizza. PI * r² = 100PI This is correct.

2. What is the area of one piece of pizza? (10/360)[(PI)10^2] = 25/9 PI No. You want 1/16 of your answer to part 1.

3. What is the area of a half-piece?(5/360)[(PI)10^2] = 25/18 PIThis would be ok if part 2 was correct, so you'll have to adjust this too.

4. What would the area of the whole pizza be if it were made of half pieces? Does this mean the original pizza? That would be unchanged from part 1. Or does it mean just the area of a half of the original, in which case answer for part 1 divided by 2

5. What is the radius of a half-piece? (ie, where do I need to cut to make two equal halves out of a piece?)The area of 16 half pieces would be answer to part 1 divided by two. Then divide by pi and square root to get the new radius. Note. It is not just half of 10.

Hope that helps.

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

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

2. What is the area of one piece of pizza? (10/360)[(PI)10^2] = 25/9 PI No. You want 1/16 of your answer to part 1.

2- confused isn't the Area of Sector = ½ × (θ × π/180) × r2 (when θ is in degrees)

the degree is 20 right? like I measured it from the circle you drew ½ × (θ × π/180) × r^2=

50/9 PI

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

4. What would the area of the whole pizza be if it were made of half pieces? it mean the original pizza

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,444

hi zee-f

The angle may seem to measure as 20 but the trouble with measuring is that isn't isn't perfectly accurate.

16 pieces at 20 degrees each is only 320 degrees.

You will get the exact angle by doing 360 / 16. (hint: it is not a whole number)

If part 4 means the whole pizza then its area is the same as it was for part 1.

But, are you sure? It seems odd to ask for the same thing twice. If, on the other hand it means the area for the half piece problem then it is helping to lead on to part 5; so it is a more logical thing to ask. But the wording does suggest what you say, I do agree. Perhaps you should ask your tutor for clarification.

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

I think I know these algebra, but.... What is FOIL?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

I'm not crazy, my mother had me tested.

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,444

hi Agnishom,

I had not met this until I joined this forum. I think it is commonly used in the USA as a way to expand two brackets each with two terms.

Let's say (a + b)(c + d)

You multiply the First terms ac

you multiply the Outers ad

You multiply the Inners bc

You multiply the Last terms bd

Then you put it all together: ac + ad + bc + bd

Bob

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

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

OoH I did that in the beginning I got 22.5

Offline

**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

22.5/360 *pi *100= 25/4pi

Offline