## Homework question

Complex numbers, rational functions, logarithms, sequences and series, matrix operations, etc.
Hell0
Posts: 24
Joined: Sun Jun 23, 2013 5:04 am
Contact:

### Homework question

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
Posts: 72
Joined: Sat Dec 29, 2012 2:42 am
Contact:

### Re: Homework question

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

### Re: Homework question

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