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Math Help - square

  1. #1
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    square

    help im stuck
    is this possible to factorise?
    3(x^2-10x+16)

    = (x+10)(x-8) ???
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  2. #2
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    Re: square

    This is obviously not correct as there was a factor of 3 that disappeared.

    I think you'll find that the two numbers that multiply to give 16 and add to give -10 are -8 and -2.
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  3. #3
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    Re: square

    Quote Originally Posted by dragon555 View Post
    help im stuck
    is this possible to factorise?
    3(x^2-10x+16)

    = (x+10)(x-8) ???
    Since 10(-8)= -80 is NOT 3(16)= 48, no those are obviously not the same.

    You could do it this way: x^2- 10x+ 16= x^2- 10x+ 25- 9= (x- 5)^2- 9 which is a "sum and difference of squares"- it is equal to ((x-5)+3)((x-5)-3)= (x-2)(x-8).

    3(x^2- 10x+ 16)= 3(x- 2)(x- 8)
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