Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Tabbiejack

  • one year ago

What is the value of c such that: x2 + 14x + c, is a perfect-square trinomial?<o:p></o:p> A. 7 B. 98 C. 196 D. 49

  • This Question is Closed
  1. passive13
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    D

  2. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[x^2+14x+c=0\]

  3. ParthKohli
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Observe that a perfect square is in the form \((a + b)^2 = a^2 + 2ab + b^2\). The first term is \(x^2 \) so we get an idea that the perfect square is in the form \((x + b)^2\). Now the middle term is \(2ab\) and here it is \(14x\). We know that \(a = x\) and so \(2x b = 14x \Rightarrow b = 7\). And so we have \((x + 7)^2 = x^2 + 14x + 49\). There's another technique which you can use formally, which is called "Completing the Square". It's just a rip-off of what I did above.

  4. ParthKohli
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    That technique says that you get the half of the coefficient of \(x\), and square it to get the last term. So you get the half of \(14\) which is \(7\). The square of that is \(49\).

  5. Jhannybean
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1369717242091:dw|

  6. Tabbiejack
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok it is easier to see it like that

  7. Tabbiejack
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I have another question if you don't mind

  8. Tabbiejack
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Graph the set of points. Which model is most appropriate for the set? ( 1, 20), (0, 10), (1, 5), (2, 2.5)

  9. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.