simple factoring: (x^2)(y^3)+xy  TOPIC_SOLVED

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simple factoring: (x^2)(y^3)+xy

Postby Tennise on Mon Jun 08, 2009 8:58 pm

I understand the numerical ones, but am having trouble with the variable ones...

It works in theory, and I can see how it would work, but when I substitute numbers for the variables, it doesn't work:
x = 2, y = 3
This was the expression: x2y3+xy
4*27+6 = 114

This was the answer: xy(xy2 + 1)
6(2*9) = 12*54 = 648
or...
6(18) = 108

Did I evaluate the equations wrong? I can't seem to get the same answer for them both...
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Re: simple factoring: (x^2)(y^3)+xy  TOPIC_SOLVED

Postby jaybird0827 on Mon Jun 08, 2009 9:01 pm

Tennise wrote:I understand the numerical ones, but am having trouble with the variable ones...

It works in theory, and I can see how it would work, but when I substitute numbers for the variables, it doesn't work:
x = 2, y = 3
This was the expression: x2y3+xy
4*27+6 = 114

This was the answer: xy(xy2 + 1)
6(2*9) = 12*54 = 648
or...
6(18) = 108

Did I evaluate the equations wrong? I can't seem to get the same answer for them both...


Let's look at


Are you sure that you plugged everything in, correctly? We know that is correct.
Do you think that is the correct evaluation of ?
Also, what is the next multiple of 6 after 108?
Assuming that the answer to the first question is "yes", the answer to the second question should tell you that the value of the second factor should be
.
Now, go back and re-evaluate
.

If you're still stuck, please reply and show your all the steps you attempted to correct your work.
Last edited by jaybird0827 on Mon Jun 08, 2009 9:17 pm, edited 2 times in total.
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Re: simple factoring: (x^2)(y^3)+xy

Postby Tennise on Mon Jun 08, 2009 9:10 pm

jaybird0827 wrote:
Tennise wrote:I understand the numerical ones, but am having trouble with the variable ones...

It works in theory, and I can see how it would work, but when I substitute numbers for the variables, it doesn't work:
x = 2, y = 3
This was the expression: x2y3+xy
4*27+6 = 114

This was the answer: xy(xy2 + 1)
6(2*9) = 12*54 = 648
or...
6(18) = 108

Did I evaluate the equations wrong? I can't seem to get the same answer for them both...


Let's look at


Are you sure that you plugged everything in, correctly? We know that is correct.


ah I see why: I ignored the +1 in the second expression! It's so easy to forget...
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Re: simple factoring: (x^2)(y^3)+xy

Postby jaybird0827 on Mon Jun 08, 2009 9:15 pm

Tennise wrote:
ah I see why: I ignored the +1 in the second expression! It's so easy to forget...


You obviously got that before I finished editing. Awesome job! :D
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