Math Is Fun Forum

Sarah Rebekah 13

Guest

Geometry.

How to do 3x+2 And 7x-2?

Can you help me with this Equation 14x + | 15/

Anakin

Member

Registered: 2009-10-04

Posts: 145

Re: Geometry.

Do what with them?
Do you mean solve for x if the equation was equal to zero? If so:

3x+2=0
3x=-2
x=-2/3

7x-2=0
7x=2
x=2/7

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry.

Hi Sarah;

Can you help me with this Equation 14x + | 15/

As Anakin pointed out above an equation is of the form 7x + 3 = 24, also there is no meaning to |15/ . Have you copied the problem correctly? Please check it again and write it exactly as it is in the book. And don't forget to check that it is correct after you have posted it.

Hurry up and do that and post right here.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Sarah Rebekah 13

Guest

Re: Geometry.

Ok thanks let go and do it.

Sarah Rebekah13

Guest

Re: Geometry.

It 7x3+2.Is that Clear

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry.

Hi Sarah Rebekah13;

If you mean this:

Then we are done.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Sarah Rebekah 13

Guest

Re: Geometry.

Yes.Thanks

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry.

Hi Sarah Rebekah 13;

Your welcome. I know they don't think this is important but get to know your times tables a little better. That will make those types of problems a breeze.

3x1 = 3
3x2 = 6
3x3 = 9
3x4 = 12
3x5 = 15
3x6 = 18
3x7 = 21
3x8 = 24
3x9 = 27

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Anakin

Member

Registered: 2009-10-04

Posts: 145

Re: Geometry.

Particularly, you should know the multiplication tables by heart for all numbers up to at least 12. When I was a bit younger, I used to do tons of multiplication in my head before falling asleep and now it's permanently set in there. Knowing them directly will help you a lot in the future in math where you have to start factoring and such.

Good luck.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry.

Hi Anakin;

I recently had a small argument with a guy who is a Physicist on another forum who believes it is not important to teach children the multiplication tables even though he learnt them. I couldn't disagree more.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Sarah Rebekah 13

Guest

Re: Geometry.

Thanks Guys.

Anakin

Member

Registered: 2009-10-04

Posts: 145

Re: Geometry.

Hi Anakin;

I recently had a small argument with a guy who is a Physicist on another forum who believes it is not important to teach children the multiplication tables even though he learnt them. I couldn't disagree more.

Yeah, he couldn't have been more wrong. Nearly everything in more complex math (not that I'm even that far) requires the use of multiplication and without having to punch in every digit into the calculator certainly saves time. For instance, division is made a lot easier with multiplication, finding LCM is easier, and even working with fractions is made a lot easier with knowledge of the multiplication tables.

Enough of my babbling now.

Last edited by Anakin (2009-12-03 19:29:41)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Geometry.

Hi Anakin;

Everything that we have said seems to be self evident. So, I couldn't understand his position at all. He is a really bright guy so I tried and tried again. I still think you will be hampered later on if you can't do basic arithmetic. I know we have calculators everywhere but I don't think you will achieve the same degree of undestanding.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Sarah Rebekah 13

Guest

Re: Geometry.

Sometime you have,to oncome Anger with love.Anakin

Devantè

Real Member

Registered: 2006-07-14

Posts: 6,400

Re: Geometry.

Powers are also quite important - I suggest you try to remember these, alongside the powers of 2 in-between;

2[sup]10[/sup] = 1024
2[sup]20[/sup] = 1048576
2[sup]30[/sup] = 1073741824 (not used a lot)

Applications of the above are very vast, but here are some basic examples of where they could be used in basic arithmetic;

32 × 16 = 2[sup]5[/sup] × 2[sup]4[/sup] = 2[sup]9[/sup] = 512
128 × 512 = 2[sup]7[/sup] × 2[sup]9[/sup] = 2[sup]16[/sup] = 65536

Squares are obviously important, too;

1² = 1
2² = 4
3² = 9
4² = 16
5² = 25
6² = 36
7² = 49
8² = 64
9² = 81
10² = 100
11² = 121
12² = 144
13² = 169
14² = 196 (it's just the 69 from 13² reversed - that's how I first remembered it)
15² = 225
16² = 256
17² = 289
18² = 324
19² = 361
20² = 400
25² = 625
30² = 900
40² = 1600
50² = 2500
100² = 10000

Those last ones aren't terribly important, since the answers can be found very easily.

On to cubes - they often saved me a lot of time if the exponent was unknown, i.e. 3[sup]x[/sup] × 4[sup]x[/sup] = 12[sup]x[/sup]

1³ = 1
2³ = 8
3³ = 27
4³ = 64
5³ = 125
6³ = 216
7³ = 343
8³ = 512 (note: 8³ = (2³)³ = 2[sup]9[/sup])
9³ = 729
10³ = 1000
11³ = 1331
12³ = 1728

That's some of what you should try to memorise, alongside the tables bobbym mentioned earlier. Arithmetic is fundamental.