Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

a123

  • 4 years ago

(x+3)^2 - (3x-1)^2 = x^3 + 4? i've tried this three times and I still get the wrong answer!

  • This Question is Closed
  1. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[(x+3)^2 - (3x - 1)^2 = x^3 + 4\]

  2. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    just to clarify

  3. jim_thompson5910
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    unless you know the cubic formula, your best bet is to use a graphing calculator to find the approximate solutions.

  4. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    we're not allowed to use a calculator. the answer is supposed to come out to be - 2/3

  5. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    but I don't know how to get there

  6. jim_thompson5910
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok so there's a typo somewhere in the problem then, my guess is that x^3 is one of the typos

  7. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait, I made a mistake typing out the problem. it's actually \[(x+3)^3\] as the first one

  8. jim_thompson5910
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    oh ok thx, one sec

  9. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so \[(x+3)^3 - (3x - 1)^2 = x^3 + 4\]

  10. jim_thompson5910
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\large (x+3)^3- (3x-1)^2 = x^3 + 4\] \[\large x^3+9x^2+27x+27- (9x^2-6x+1) = x^3 + 4\] \[\large x^3+9x^2+27x+27- 9x^2+6x-1 = x^3 + 4\] \[\large x^3+9x^2+27x+27- 9x^2+6x-1 - x^3 - 4=0\] \[\large 33x+22=0\] \[\large 33x=-22\] \[\large x=-\frac{22}{33}\] \[\large x=-\frac{2}{3}\]

  11. a123
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thank you! i see exactly where I went wrong.

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

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy