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Cranberry557
06-08-2009, 11:12 AM
Hi, i am a 8th grade student and am in Algebra I. I need help simplifying the expression: 20x^3y/ 4xy^2 * -6yx/-x
( the * is a multiplication sign) The first thing that i tried to so is simpilify 20 and 4 which is 5 and then subtract x^3 and x^2 to get just "x". Then i subtracted y and y^2 and got -y. my final answer i got was 5x^2/y. can you tell me if this is correct please?

Subhotosh Khan
06-08-2009, 11:16 AM
Hi, i am a 8th grade student and am in Algebra I. I need help simplifying the expression: 20x^3y/ 4xy^2 * -6yx/-x
( the * is a multiplication sign) The first thing that i tried to so is simpilify 20 and 4 which is 5 and then subtract x^3 and x^2 to get just "x". Then i subtracted y and y^2 and got -y. my final answer i got was 5x^2/y. can you tell me if this is correct please?

First - let us re-write your problem

Simplify:

\frac{20x^3y}{4xy^2} \cdot \frac{-6yx}{-x}

Is this the statement of your problem?

Cranberry557
06-08-2009, 03:26 PM
Yes, that is the correct way the problem is written.

Denis
06-08-2009, 03:34 PM
20x^3 y / (4x y^2)

Do you agree that simplifying that one leaves 5x^2 / y ?

Cranberry557
06-08-2009, 05:13 PM
Yes i do agree

Aladdin
06-09-2009, 03:56 AM
I also do agree :)

Denis
06-09-2009, 09:54 AM
20x^3 y / (4x y^2) * -6yx / -x NOTE: the set of brackets I've inserted is a MUST; agree?

OK; so we agree that 20x^3 y / (4x y^2) = 5x^2 / y

Similarly, -6yx / -x = 6y ; agree?

So we now have 5x^2 / y * 6y, or 30x^2 y / y ; right?

I'll let you have the fun of finishing it!

By the way, you can check yourself if your ending simplification is correct by assigning any
values to x and y, say x=5 and y=2, then substituting these in the original expression and
in the simplification: both should end up with same value...kapish?

Cranberry557
06-09-2009, 08:20 PM
Okay so then you get 5x^2/y */ 6y/1 and you cancel out the y's and you multiply 5 and 6 for get a final answer of 30x^2 ? I also have a quick question that doesn't have to do with this problem, what is a discriminate? Thanks for all your help!

Subhotosh Khan
06-09-2009, 08:22 PM
Okay so then you get 5x^2/y */ 6y/1 and you cancel out the y's and you multiply 5 and 6 for get a final answer of 30x^2 ? I also have a quick question that doesn't have to do with this problem,

what is a discriminate? <<< do a google search

Thanks for all your help!

Mrspi
06-09-2009, 08:30 PM
Okay so then you get 5x^2/y */ 6y/1 and you cancel out the y's and you multiply 5 and 6 for get a final answer of 30x^2 ? I also have a quick question that doesn't have to do with this problem,

what is a discriminate? <<< do a google search

Thanks for all your help!

I agree that a Google search should be helpful. But, I think you will want to search under the correct spelling, which is discriminant