math... Ms, Sue can you help?

posted by .

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? -

    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.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math

    I am doing something wrong when I work this question. Can someone show me the steps. I have the answer. x<5.189 The sum of the costs in parts a and c is less than $120. Write and solve an inequality to determine the possiblities …
  2. introductory algebra

    I had these problems on my test and for some reason got them wrong. Here are the problems: Solve: x-y=9 x+y=1 The test states that the answer is (5,-4) I've checked ,y work and used substitution to solve this and still get x=4, y=-5. …
  3. Fractions

    Hi Sue, That's the same answer I got, but for some reason I got it wrong on one of my test and I'm not sure why.
  4. math To MS.SUE

    Ms sue i really want a hundred percent on one algebra test im in algebra and im so smart and good at math but the thing is in my class we tooken 4 tests and on all of then i only got one wrong whit the most minor common mistake i don't …
  5. math

    I asked sue a question yesterday and don't understand the answer can you explain?
  6. Maths

    There was a question: A gallon jug of milk is 3/4 full. After breakfast, you drink 1/12 of the milk. What fraction is the gallon is left?
  7. General Math I

    Hi Ms. Sue this is Shayna here. I am writing you this time, because I am very confused in a question of a test I just took this was the question Susan wants to buy a paddle boat for $840. She will pay 20% down and pay the rest in six …
  8. To Ms. Sue

    Hey Ms. Sue! I've got a question How well do you know everybody's questions?
  9. Math

    ella took a biology test of 54 question. She got 5/6 with a question correct how many questions did she get wrong on her biology test?
  10. Esol

    hi . I did my test yesterday and now trying to see if my answer were rights about some questions I'm bad at grammer. thanks alot if you helping me jiskha com 1-It will take a lot more than that to make --- run that far.me / i / myself/mine …

More Similar Questions