Posted by **miss b** on Wednesday, December 19, 2012 at 8:47pm.

Apparently, I got this question wrong on a test and I'd like to know what error I made... can you help?

Here's what I did:

2b^2+b=6

b^2+1/2b=3

b^2+1/2b+(1/2)^2=3+(1/2)^2

(b+1/2)^2=3+1/4

b+1/2=+/- <13/4>

b=-1/2+/-<13>/2

b=(-1+/-<13>)/2

<> means its in a radical and +/- means plus or minus

- math... Ms, Sue can you help? -
**Reiny**, Wednesday, December 19, 2012 at 10:31pm
The error is in your third line

you take 1/2 of the middle coefficient, and then square it

(1/2)(1/2) = 1/4 --- (1/4)^2 = 1/16

3rd line:

b^2 + (1/2)b + 1/16 = 3 + 1/16

(b+1/4)^2 = 49/16

b + 1/4 = ± 7/4

b = -1/4 ± 7/4 = 6/4 or -8/4

**b = -2 or 3/2**

since we have rational answers, we know it would have factored to

(x+2)(2b-3)

= 2b^2 + b - 6 , the original.

## Answer This Question

## Related Questions

- math To MS.SUE - Ms sue i really want a hundred percent on one algebra test im ...
- math - I asked sue a question yesterday and don't understand the answer can you ...
- General Math I - Hi Ms. Sue this is Shayna here. I am writing you this time, ...
- introductory algebra - I had these problems on my test and for some reason got ...
- Fractions - Hi Sue, That's the same answer I got, but for some reason I got it ...
- Maths - There was a question: A gallon jug of milk is 3/4 full. After breakfast...
- Math - ella took a biology test of 54 question. She got 5/6 with a question ...
- math - I am doing something wrong when I work this question. Can someone show me...
- To Ms. Sue - Hey Ms. Sue! I've got a question How well do you know everybody's ...
- Physics - Hello, I need some help with this physics problem. This was the only ...

More Related Questions