Homework question

Complex numbers, rational functions, logarithms, sequences and series, matrix operations, etc.
Hell0
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Homework question

Postby Hell0 » Sun Sep 01, 2013 5:42 am

Hey i'd appreciate it if anyone could help me with this question.

If (x-2A)(2x+1)=2x2-Bx+10, then A • B =

thanks a lot

jg.allinsymbols
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Re: Homework question

Postby jg.allinsymbols » Sun Sep 01, 2013 7:28 am

Hell0 wrote:Hey i'd appreciate it if anyone could help me with this question.

If (x-2A)(2x+1)=2x2-Bx+10, then A • B =

thanks a lot



Perform the multiplication indicated by the lefthand member. Arrange the result into decreasing order of the variable, x. You will look at coefficients of terms in corresponding positions to find A and B.

Hell0
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Joined: Sun Jun 23, 2013 5:04 am
Contact:

Re: Homework question

Postby Hell0 » Sun Sep 01, 2013 4:41 pm

Hi. this is what i tried


x - 4Ax = -Bx

and

-2A = 10

found a:

A = -5

then plugged it in:

x - 4(-5)x = -Bx
x + 20x = -Bx

pulled out the x because they all have it:

x + 20x = -Bx
1 + 20 = -B
-B = 21
B = -21

-21 * -5 = 105

The answer is 105?

theshadow
Posts: 102
Joined: Sun Feb 22, 2009 11:12 pm

Re: Homework question

Postby theshadow » Sun Sep 01, 2013 7:20 pm

Hell0 wrote:The answer is 105?

yeh, that's what I get too


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