Homework question  TOPIC_SOLVED

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

Homework question

Postby Hell0 on 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
Hell0
 
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Re: Homework question

Postby jg.allinsymbols on 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.
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Re: Homework question  TOPIC_SOLVED

Postby Hell0 on 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?
Hell0
 
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Re: Homework question

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

Hell0 wrote:The answer is 105?

yeh, that's what I get too
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