1. ## Homework question

Hi everyone, first post here

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

if this is in the wrong subforum sorry, its precalc homework so i put it here

2. ## Re: Homework question

Hey Hell0.

Hint: Try expanding both sides and multiply both sides by A so that you can match up the AB term and use the rest of the variables to solve for A,B (remember that in a quadratic, you have fx^2 + gx + c with three constants f,g,c).

3. ## 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

4. ## Re: Homework question

( x- 2A )( 2x + 1 ) = 2x^2-Bx +10
2x^2 +x - 4Ax - 2A = 2x^2-Bx +10
2x^2 + ( 1 - 4A ) x - 2A = 2x^2-Bx +10
Now compare the coefficients and conclude.
You will get A*B = 105

5. ## Re: Homework question

hey thanks everyone. can you try to help me with this one? Pre-calc question? its the only blank question i have left. id really appreciate it

*solved*