Discriminant

Use the discriminant to determine how many real-number solutions the equation has 1 - 7a2 = -7a - 2

A) 2
B) 1
C) 0
Not sure how to work this problem

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asked by Lisa D
  1. rearrange it.

    7a^2+7a+2=0

    discriminate= 49-4*7*2= negative number, no real solutions.

  2. First arrange the terms in the standard form of a quadratic:
    1 - 7a2 = -7a - 2
    7a²-7a-3=0
    The variable is a, and the coefficients of the a², a and constant terms are respectively
    A=7, B=-7, C=-3

    The discriminant is the expressino
    D=(B²-4AC)
    and the roots of the equation are:
    X1,X2= (-B±√(B²-4AC))/2A
    Therefore
    if D>0, there are two roots, if D=0, there is one root (actually two coincident roots), and if D<0, the roots are complex, or generally considered "no root".

    Post your answer for checking if you wish.

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  3. Rewrite your equation in standard form:
    7a^2 -7a -3 = 0

    They are trying to confuse you by using a as a variable. Think of your equation as
    7x^2 -7x -3 = 0
    It does not matter what symbol you giove to the unknown variable; just don't call it "a".

    The numbers a, b, and c in the equation are 7, -7 and -3.
    The discriminant is b^2 -4ac = 49+84 = -133
    Since it is positive, there are two real solutions.
    They are
    x = (1/14)(7 +/- sqrt(133)]= 1.324 and
    -0.324

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    posted by drwls
  4. Thanks for the Explaning this problem drwls. Ok, the first time I worked the problem I got 0 then I reworked it and got 1

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    posted by Lisa D
  5. -133 should be 133 in my previous answer.
    There is NOT one root. There are two, if I did the numbers right.

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    posted by drwls
  6. Ok, I got it. Sorry been having problems w/ this site.Thanks I got more..

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    posted by Lisa D

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