(20b(squared)-11b-3)

Sorry I don't know how to type the squared symbol...but thanks in advance!

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- Apr 15th 2008, 11:19 AMcurlysueFactoring and impossible equation!!!
(20b(squared)-11b-3)

Sorry I don't know how to type the squared symbol...but thanks in advance! - Apr 15th 2008, 11:26 AMangel.white
- Apr 15th 2008, 11:26 AMtopsquark

Multiply the coefficient of the leading term by the constant term:

20 * -3 = -60

List all the pairs of factors of -60:

1, -60

2, -30

3, -20

4, -15

5, -12

6, -10

10, -6

12, -5

15, -4

20, -3

30, -2

60, -1

Now we want to find the pair of factors in the list above that add up to be equal to the coefficient of the linear term, in this case -11. (If no such pair of factors is in the list then you cannot factor the quadratic.)

I've got 4 + -15 = -11.

So split the linear term of the quadratic into -11x = 4x - 15x.

Group the terms as follows:

Now factor from each group:

and note that both terms have a common factor, 5b + 1, so we can factor that from each term as well:

There you go!

-Dan - Apr 15th 2008, 11:30 AMangel.white
- Apr 15th 2008, 11:31 AMred_dog
- Apr 15th 2008, 11:41 AMwingless
If you can't see how to factorize, you can use this:

Multiplying by 4.5 gives

- Apr 15th 2008, 11:44 AMred_dog
- Apr 15th 2008, 12:12 PMtopsquark