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Math Help - Factoting Trinomials

  1. #1
    Newbie dizzycarly's Avatar
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    Factoting Trinomials

    Ok, other post already. How on earth do I plan to past my final. *stresss* Anyways I don't remember how to factor Trinomials in the form of :


    Ax(squared) + bx + c

    so how do I solve?

    3x(squared) + 10x + 8

    P.S. sorry but I don't know how to get the squared thing.
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  2. #2
    Junior Member
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    Quote Originally Posted by dizzycarly View Post
    Ok, other post already. How on earth do I plan to past my final. *stresss* Anyways I don't remember how to factor Trinomials in the form of :


    Ax(squared) + bx + c

    so how do I solve?

    3x(squared) + 10x + 8

    P.S. sorry but I don't know how to get the squared thing.
    Are you asking how to solve for x or how to factorize it? Anyways, to solve for x, you have:

    3x² + 10x + 8 where

    a = 3;
    b = 10;
    c = 8
    ;

    Quadratic formula is the following:

    x_1, x_2 = -b \pm \frac {\sqrt {b^2-4ac}}{2a}

    To factorize it, you can use the box method:

    3x² + 10x + 8

    What multiplied by what gives 24 (a*c or 8*3), and added up gives 10 (b)? Obviously, in this case, 6 and 4.

    3x² + 6x + 4x + 8;
    (3x²+6x) + (4x+8);
    3x(x+2) + 4(x+2);
    (3x+4)(x+2)
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  3. #3
    No one in Particular VonNemo19's Avatar
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    Detroit, MI
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    1,823
    Quote Originally Posted by dizzycarly View Post
    Ok, other post already. How on earth do I plan to past my final. *stresss* Anyways I don't remember how to factor Trinomials in the form of :


    Ax(squared) + bx + c

    so how do I solve?

    3x(squared) + 10x + 8

    P.S. sorry but I don't know how to get the squared thing.
    Let's look at this

    (rx+s)(x+t)

    if we foil we get

    rx^2+rtx+sx+st
    =rx^2+(rt+s)x+st

    So, when factoring a quadratic trinomial, we must look for all factors of the first an last term whose sums add up to be the coefficient of the linear term.

    In your case we can analyze as follows:

    3x^2+10x+8

    3 only has two factors, this makes things easier. 8 has factors, 1\cdot8,2\cdot4.

    Our possiblities are then

    (3x+1)(x+8) NO

    (3x+8)(x+1) NO

    (3x+2)(x+4) NO

    (3x+4)(x+2) Yes =3x^2+6x+4x+8=3x^2+10x+2

    This takes practice to get good at, so my advice to you is to hit the books!
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