check my precalc

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#1. solve x^2-1<0 I got (-1,1)

#2 x(x+1) >20
I got (-infinity, -4) U (5,infinity)

#3
what is the domain of this function? f(x)= squre root of (x-3x^2)
i got [-1/3,0]

thanks!!!

  • check my precalc -

    #1
    correct

    for #2
    x^2 + x - 20 > 0
    (x+5)(x-4) > 0
    critical values are -5 and +4
    In my notation it would be
    x < -5 OR x > 4

    Your (-infinity, -4) U (5,infinity) should then be
    (-infinity, -5) U (4,infinity)

    #3
    correct

  • check my precalc -

    Thanks so much!

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