I have a few problems i need help with. . .

[erin524]

the instructions just say to simplify. These are 3 separate problems.

1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15



2) (125x^6y-75x^5y+25x^4-40x^2) division symbol (-25x^3)



3) 16x^-2-12x^-1/20^-3-15x^-2



i have a few more, I'll put them on a separate post.

 

[Denis]

1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15

Please check your posts: brackets required?

Like, should that be: (4x-5)/(x^2+4x 21) - (3x+2)/(x^2-8x+15)

 

[Deleted member 4993]

the instructions just say to simplify. These are 3 separate problems.

1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15



2) (125x^6y-75x^5y+25x^4-40x^2) division symbol (-25x^3)



3) 16x^-2-12x^-1/20^-3-15x^-2



i have a few more, I'll put them on a separate post.

Use the methods discussed in:

viewtopic.php?f=9&t=35115

then let us know where you stand.

Please show your work, indicating exactly where you are stuck - so that we know where to begin to help you.

 

[fasteddie65]

1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15

I think you mean (4x - 5)/(x^2 + 4x - 21) - (3x + 2)/(x^2 - 8x + 15) =
(4x - 5)/[(x + 7)(x - 3)] - (3x - 2)/[(x - 3)(x - 5) =
(4x - 5)(x - 5)/[(x + 7)(x - 3)(x - 5)] - (3x - 2)(x + 7)/[(x + 7)(x - 3)(x - 5)] =
(4x^2 - 25x + 25)/[(x + 7)(x - 3)(x - 5)] - (3x^2 + 19x - 14)/[(x + 7)(x - 3)(x - 5)] =
(x^2 - 44x + 39)/[(x + 7)(x - 3)(x - 5)]

 

[Aladdin]

i have a few more, I'll put them on a separate post.

Surely , without showing no work ... I guarantee , that you are having no benifet from what instructors pointed or helped you :wink:

 

[Loren]

As you have posted,
1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15 means \(\displaystyle 4x-\frac{5}{x^2}+4x-21-3x+\frac{2}{x^2}-8x +15\).

I am sure that is not the problem as originally stated. I think you need to learn the "order of operations convention" so that you can post a problem properly, using grouping symbols, as suggested by others above. You might consider googling "Order of Operations".

 

[erin524]

1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15

Please check your posts: brackets required?

Like, should that be: (4x-5)/(x^2+4x 21) - (3x+2)/(x^2-8x+15)

There are no brackets it is 2 fractions.


4x-5 is the numerator

x^2+4x 21 is the denominator

this fraction is subtracted by

3x+2 numerator

x^2-8x+15 denominator

 

[erin524]

i have a few more, I'll put them on a separate post.

Surely , without showing no work ... I guarantee , that you are having no benifet from what instructors pointed or helped you :wink:

This is not for a class, these problems are off of a review sheet for a placement test. I took the class 12 years ago, and I thought if I saw these problems solved, it would jog my memory and I will be able to solve similar ones on my own.

 

[Loren]

<<<There are no brackets it is 2 fractions.


4x-5 is the numerator

x^2+4x 21 is the denominator

this fraction is subtracted by

3x+2 numerator

x^2-8x+15 denominator


This is how that is typed in to be clear as to what is meant...

(4x-5)/(x^2+4x 21) - (3x+2)/(x^2-8x+15)

This means \(\displaystyle \frac{4x-5}{x^2+4x 21}-\frac{3x+2}{x^2-8x+15}\)

It will pay you dividends and get quicker responses to your questions if you learn to use grouping symbols correctly.

 

[Deleted member 4993]

the instructions just say to simplify. These are 3 separate problems.

1) 4x-5/x^2+4x-21 - 3x+2/x^2-8x+15



2) (125x^6y-75x^5y+25x^4-40x^2) division symbol (-25x^3)

Is this

\(\displaystyle \frac{125x^6y \, - \, 75x^5y \, + \, 25x^4 \, - \, 40x^2}{-25x^3}\)

3) 16x^-2-12x^-1/20^-3-15x^-2 <<< Did you type this correctly?

Is this

\(\displaystyle \frac{16x^{-2} \, - \, 12x^{-1}}{20^{-3} \, - \, 15x^{-2}}\)


i have a few more, I'll put them on a separate post.

 

[Denis]

Erin, SLOW DOWN and listen...

4+6/2 = 4 + 3 = 7

(4+6)/2 = 10/2 = 5

Now do you "see" the importance of brackets?