1. SDN Mobile is now free on iTunes and on the Google Play Store. Enjoy!
    Dismiss Notice
  2. This Wednesday we're hosting our first-ever Instagram takeover with UF College of Dentistry student, Carson. Follow @studentdoctornetwork on Instagram to get a glimpse of life as a D1, ask questions and more!
    Dismiss Notice
  3. This forum is for support and discussion only. Please promote test prep materials/services (including AMAs) in the Special Offers subforum only. Thanks!
    Dismiss Notice
  4. Guest, be sure to check out How To Get Into Dental School, our free downloadable PDF with step-by-step details for dental school applicants!
    Dismiss Notice

algebraic problem

Discussion in 'DAT Discussions' started by BodybldgDoc, Apr 17, 2007.

  1. BodybldgDoc

    BodybldgDoc Guest

    Joined:
    Jan 13, 2007
    Messages:
    712
    Likes Received:
    0
    Status:
    Pre-Health (Field Undecided)
    How do we solve this?

    The nonzero numbers a and b are such that a=b^4. If the value of b is tripled, the new value is which of the following.
    a. a raised to the 4th power
    b. a multiplied by 3
    c. a multiplied by 4
    d. a multiplied by 12
    e. a multiplied by 81
     
  2. DDSDakoo

    10+ Year Member

    Joined:
    Feb 27, 2007
    Messages:
    56
    Likes Received:
    0
    im gonna take a staaab it at this.

    i think the answer is E.

    reasoning:
    if a=b^4

    then if you plug in 1 for a and b. you get:
    1=1^4
    then you triple B (1 * 3) right?
    a=3^4
    a=81

    i hope that makes sense! i hope more that its right! haha
     
  3. DDSDakoo

    10+ Year Member

    Joined:
    Feb 27, 2007
    Messages:
    56
    Likes Received:
    0
    ok i just had a friend explain this to me, the end of it sort of didnt make sense in my head

    if A=B^2,
    then you double B, what is the new value:

    A=2B^2

    A=4B

    the answer would be: A multiplied by 4

    since it is an equality equation. what you do to one side, you have to do to the other.

    so correction:
    if A= (3^4)b
    then A would be multiplied by a factor of 81. since the equality had changed when you multiplied by a factor of 3 on the side of b^4.
     
  4. Streetwolf

    Streetwolf Ultra Senior Member
    Dentist 7+ Year Member

    Joined:
    Oct 25, 2006
    Messages:
    1,801
    Likes Received:
    6
    Status:
    Dentist
    You just sub in 3b for b and see what happens, since 3b is b tripled:

    Instead of b^4 you have (3b)^4 which equals 3^4*b^4 = 81b^4.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  5. OP
    OP
    BodybldgDoc

    BodybldgDoc Guest

    Joined:
    Jan 13, 2007
    Messages:
    712
    Likes Received:
    0
    Status:
    Pre-Health (Field Undecided)
    If A=(2B)^2 then wouldnt it be A=4B^2?
     
  6. OP
    OP
    BodybldgDoc

    BodybldgDoc Guest

    Joined:
    Jan 13, 2007
    Messages:
    712
    Likes Received:
    0
    Status:
    Pre-Health (Field Undecided)
    but the answer says a multiplied by 81. How do they get a? The correct answer is e though
     
  7. DDSDakoo

    10+ Year Member

    Joined:
    Feb 27, 2007
    Messages:
    56
    Likes Received:
    0
    yeah you are right. clarity at last!
     
  8. DDSDakoo

    10+ Year Member

    Joined:
    Feb 27, 2007
    Messages:
    56
    Likes Received:
    0
    ok i "think" i got it.

    so if a= (3b)^4

    then you change the right side of the equation like this when you increase the factor of 3:
    what you do on the right side, you must do on the left.
    a = (3^4)b^4 ; (3^4) being the part u introduced into the equation.
    (3^4)a= 81b^4

    81*a=81b^4
     
  9. OP
    OP
    BodybldgDoc

    BodybldgDoc Guest

    Joined:
    Jan 13, 2007
    Messages:
    712
    Likes Received:
    0
    Status:
    Pre-Health (Field Undecided)
    yeah that makes sense. thanks dakoo and street
     
  10. Streetwolf

    Streetwolf Ultra Senior Member
    Dentist 7+ Year Member

    Joined:
    Oct 25, 2006
    Messages:
    1,801
    Likes Received:
    6
    Status:
    Dentist
    Take 3b as your tripled value of b. Plug in:

    a_original = b^2 (original)
    a_new = (3b)^2 (b is tripled)
    a_new = 81b^2.

    But we know a_original = b^2 so sub that in:

    a_new = 81*a_original.

    The new value of a is 81 times the original value of a.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  11. DDSDakoo

    10+ Year Member

    Joined:
    Feb 27, 2007
    Messages:
    56
    Likes Received:
    0

Share This Page