Simple Math problem help

[noisebomb44]

So ive been kind of scared of posting boring questions like math on this forum although this time its a real emergency, my brain doesnt work, and i have to solve this problem

anyway, can someone please show me how to solve this math problem, and please provide me with as many notes as possible

 

 

"factorize the expression"

xy(1+x)-(1+x)

 

and apparantly according to the book, its supposed to be 

(xy-1)(1+x)

 

 

 

What i tried to do: 

 

xy(1+x)-(1+x)

 

xy = t

 

t(1+x)-(1+x)

t+x²*y - (1+x)

xy + x²*y - (1+x)

xy + x²*y - (1+x)

x(y + xy) - x(1)+1

y+xy - 1+1

y+xy

 

But it didnt work

 

Thanks for helping me

[Leonard]

How did you get xy(1+x)-(1-x) equals xy=t  how did you get a t. You just can't add things to "help".

Firstly you need to remove the parenthesis via multiplying what is outside the parenthesis to what is inside the parenthesis, then do the subtraction.

 

Your answer could also be (1+x)(xy−1), it is the same as the books answer it just depends on who you cross multiply.

Edited September 5, 2015 by Leonard

[noisebomb44]

How did you get xy(1+x)-(1-x) equals xy=t  how did you get a t. You just can't add things to "help".

Firstly you need to remove the parenthesis via multiplying what is outside the parenthesis to what is inside the parenthesis, then do the subtraction.

i didnt add t

t = x*y, it was just to simplify things, you see that i add it back later

 

t+x2*y - (1+x)

xy + x2*y - (1+x)

 

also with your second tip, it would look like this

 

xy(1+x)-(1+x)

xy+x²y-(1+x)

xy+x²y-1-x

 

And then i cant go any further

 

edit, although if i factored the answer, it would look like this

x(y+xy-1) - 1

[colonel_mortis]

For simplicity, lets let (1+x) = p. That makes the original expression xyp-p. If we now factorise that to take the ps out, it becomes p(xy-1). If we substitute the (1+x) back into p, we get the expression that you were expecting, (1+x)(xy-1)

Hopefully that makes a bit more sense to you.

[colonel_mortis]

 

That wolfram answer just expands the brackets, collapses them again, then says "factorise it". Step 3 is identical to step 1.

It proves that the answer is correct, but it's not really helpful for the OP.

[TomvanWijnen]

This is what the app "Photomath" says.

 

[Leonard]

 

also with your second tip, it would look like this

 

xy(1+x)-(1+x)

xy+x²y-(1+x)

 

What you for got to do is remove the last set of parenthesis using the - sign as well, which would give you xy+x2y-1-x and not xy+x2y-(1+x)

 

This is a great site for help with math. 

Edited September 5, 2015 by Leonard

[noisebomb44]

For simplicity, lets let (1+x) = p. That makes the original expression xyp-p. If we now factorise that to take the ps out, it becomes p(xy-1). If we substitute the (1+x) back into p, we get the expression that you were expecting, (1+x)(xy-1)

Hopefully that makes a bit more sense to you.

ah, ok never thought about turning (1+x) into "p"

i got it now

[noisebomb44]

What you for got to do is remove the last set of parenthesis using the - sign as well, which would give you xy+x2y-1-x and not xy+x2y-(1+x)

yeah, but still its far from the easiest way to do it

and i would have to factorize it back to get (xy-1)(1+x) after that

[Leonard]

yeah, but still its far from the easiest way to do it

and i would have to factorize it back to get (xy-1)(1+x) after that

Yes and that way you won't make any mistakes.

[noisebomb44]

This is what the app "Photomath" says.

 

will try this app in the future, although maybe you used the wrong options, since the equation almost got longer than it was in the beginning

[noisebomb44]

Yes and that way you won't make any mistakes.

on most of my test, time is more valuable than accuracy

[colonel_mortis]

ah, ok never thought about turning (1+x) into "p"

i got it now

You don't need to substitute it for anything else, but if you're struggling to figure out the solution and you know the answer that you're looking for, it's well worth finding things that clearly haven't changed between the question and the answer and replacing them with a single letter to simplify the algebra. The idea is that eventually you get good enough at it that you never need to substitute.

 

will try this app in the future, although maybe you used the wrong options, since the equation almost got longer than it was in the beginning

A lot of apps do end up overcomplicating it because they will have set ways to do things, and they probably won't be the most efficient way to do any particular question.

[Yuval]

Simple? shiit

[noisebomb44]

Simple? shiit

simple as in not rocket science

 

although it probably is rocket science if you haven't had the math course that explains it

[Yuval]

simple as in not rocket science

 

although it probably is rocket science if you haven't had the math course that explains it

 

I did, just realized how little I remember from school, it's only been 3 months

[Nineshadow]

But it's so easy...

xy(1+x)-(1+x) = (1+x)(xy-1)

without any other necessary steps.

 

Replace 1+x with z if you still don't see it.

 

xyz - z = z(xy-1)=(1+x)(xy-1)

 

It's just the simple factoring.

[noisebomb44]

But it's so easy...

xy(1+x)-(1+x) = (1+x)(xy-1)

without any other necessary steps.

 

Replace 1+x with z if you still don't see it.

 

xyz - z = z(xy-1)=(1+x)(xy-1)

 

It's just the simple factoring.

You know how you cant see the simplest problem untill someone points it out for you, that is what happened to me here, and i knew that it was going to be a really simple answer, so thats why i wrote it in the title

Thanks to all of you who wrote different ways to solve this, i think its really going to help me get through this mess

[Nineshadow]

You know how you cant see the simplest problem untill someone points it out for you, that is what happened to me here, and i knew that it was going to be a really simple answer, so thats why i wrote it in the title

Thanks to all of you who wrote different ways to solve this, i think its really going to help me get through this mess

I know that feeling when you miss probably the simplest thing ever, but come on, this is really easy.  I mean, I learned about it in the beginning of the 5th grade.

[noisebomb44]

I know that feeling when you miss probably the simplest thing ever, but come on, this is really easy.  I mean, I learned about it in the beginning of the 5th grade.

This equation is from a 11th grade book

(aka second year high school - civil engineering)

[Nineshadow]

This equation is from a 11th grade book

(aka second year high school)

Forgot to mention school is Romania is a lot harder than in most other countries.

These are some problems we had at a test in the beginning of the 9th grade (1st year of high school, ) :

1.Demonstrate that is divisible by 19 whatever value of n (natural)

2.Demonstrate that  (n natural and bigger or equal to 2)

3. [] = ?

where [x] is the smallest integer smaller or equal to x.

4. Calculate 

5. a + b + c + d = 1

Demonstrate that < 8

6.Calculate 

7.Demonstrate that 

8.Demonstrate that >= 3/2  ( Nesbit's inequality)

9.Demonstrate that x_n < 1 for whatever X_n = 

 

These are pretty damn easy for me now and we've moved on onto more complicated stuff, so...

[noisebomb44]

Forgot to mention school is Romania is a lot harder than in most other countries.

These are some problems we had at a test in the beginning of the 9th grade (1st year of high school, ) :

1.Demonstrate that is divisible by 19 whatever value of n (natural)

2.Demonstrate that  (n natural and bigger or equal to 2)

3. [] = ?

where [x] is the smallest integer smaller or equal to x.

4. Calculate 

5. a + b + c + d = 1

Demonstrate that < 8

6.Calculate 

7.Demonstrate that 

8.Demonstrate that >= 3/2  ( Nesbit's inequality)

9.Demonstrate that x_n < 1 for whatever X_n = 

 

These are pretty damn easy for me now and we've moved on onto more complicated stuff, so...

"a + b + c + d = 1"

What?

it could be anything

0,25+0,25+0,25+0,25

etc

 

edit: aha i see, there where more to that question

 

also, atleast in sweden, 9th grade is still in elementary school, and some of these i could actually do in 9th grade, although most of them are extremely overcomplicated 

 

and, would you really need this knowledge in real life even if everyone chose civil engineer, and other math heavy educations (if that is what those are targeted towards) i mean here in sweden we have way easier calculations and even then there is a lot of shit i will never get to use, this looks like an extremely uneffective way to educate kids

[ALwin]

But it's so easy...

xy(1+x)-(1+x) = (1+x)(xy-1)

without any other necessary steps.

 

Replace 1+x with z if you still don't see it.

 

xyz - z = z(xy-1)=(1+x)(xy-1)

 

It's just the simple factoring.

 

LOL are they all serious, your solution was the fastest and simplest.

[noisebomb44]

LOL are they all serious, your solution was the fastest and simplest.

did anyone say it was not?