If (x-2A)(2x+1)=2x

^{2}-Bx+10, then A • B =

thanks a lot

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

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

thanks a lot

If (x-2A)(2x+1)=2x

thanks a lot

- Hell0
**Posts:**24**Joined:**Sun Jun 23, 2013 5:04 am

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

If (x-2A)(2x+1)=2x^{2}-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.

- jg.allinsymbols
**Posts:**71**Joined:**Sat Dec 29, 2012 2:42 am

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?

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
**Posts:**24**Joined:**Sun Jun 23, 2013 5:04 am

Hell0 wrote:The answer is 105?

yeh, that's what I get too

- theshadow
**Posts:**82**Joined:**Sun Feb 22, 2009 11:12 pm

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