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HELP! No idea how to do this...?

The questions are:

Solve these inequalities:

a) (2x-5) / (x+1) < 1

b) (2x-7) / (x+5) > 4

I have no idea how you would approach these. I would be very grateful if someone could help me and explain fully how they got the answer.

1 Answer

Relevance
  • 9 years ago
    Favorite Answer

    a) (2x-5) / (x+1) < 1

    We want to simplify this by multiplying both sides by (x+1). However, if (x+1) is negative, this will change the direction of the inequality, so we have to take the cases x>-1 and x<-1 separately.

    If x>-1, x+1 is positive:

    2x-5 < x+1, so x-5 < 1, so x < 6.

    So inequality a) is true for -1 < x < 6.

    If x<-1, x+1 is negative:

    2x-5 > x+1, so x > 6.

    But x<-1 and x>6 contradict each other, so there are no values of x<-1 satisfying inequality a).

    Final answer: -1 < x < 6.

    b) is very similar; you have to take the cases x>-5 and x<-5 separately. The answer you end up with is -6.5 < x < -5.

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