How do you factor x^2-7x-8 ?

Can you show me the steps and final answer. I hate factoring!!!!!!

Comments

  • What multiples to -8 and adds to -7? You know you're going to have one positive and one negative. How about -8 and +1.

    (x-8)(x+1)

  • (x-8)(x-1)

    This is a regular trinomial. The A value X, is 1.

    Find 2 numbers that multiply to -8 and add up to -7

    Well lets look at -8's factors

    4 and -2

    -4 and 2

    8 and -1

    -8 and 1

    Now out of these 4 possible combinations, one of them must add up to -7

    Find that. It is the third one, -8 and 1.

    Therefore you will create two brackets with x and those numbers to get back to the original equation when you FOIL.

    (X-8)(X+1)

  • Very simple.

    Step 1: x^2 - 7x - 8

    Step 2: (x-8)(x+1)

    Step 3: x-8=0 & x+1=0

    Step 4: x=8 & x=-1 are the answers.

  • x^2: the factors of 1 are 1*1

    -8: the factors are -8*1 or -4*2 or -2*4 or 8*-1

    1.....8

    1.....-1 (-1+8=7)

    1.....-8

    1.....1 (1-8=-7)

    1.....4

    1.....-2 (-2+4=2)

    1.....-4

    1.....2 (-4+2=-2)

    Only the second one equals -7, and therefore factors are -8, 1

    ANSWER: (x-8)(x+1)

    Tried my best to explain it online...but its much better if you ask your teacher about factoring since she/he can show you on paper.

  • You have to ask yourself, what multiplys to -8 and can add or subtract to -7....

    1 and -8 multiply to -8 & 1 and -8 can add or subtract to -7

    Factored form: (x-8)*(x+1)

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