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Precalculus

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1. Determine the interval(s) on which x^2 + 2x -3>0

a)x<-3, x>1
b)-3<x<1
c)x<-3, -3<x<1, x>1
d) x>1

Answer is D, x>1
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2. Determine when the function f(x)= 3x^3 + 4x^2 -59x -13 is greater than 7.

a) -5<x<1/3
b) -5<x<-1/3, x>4
c) x<4
d) x=-5, -1/3,4

Answer is: B
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3. Provde the intervals you would check to determine when -5x^2 + 37x> -15x^2 + 12x + 15.

a) x=3, x=-0.5
b) x<-3, -3<x<0.5, x>0.5
c) x<-1, -1<x<15, x>15
d) x= 1, x=15
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  • Precalculus - ,

    1. Correct.

    2. Correct.

    3. -5x^2 + 37x > -5x^2 + 12x + 15.
    -5x^2 + 5x^2 + 37x - 12x > 15,
    Combine like-terms:
    25x > 15,
    X > 15/25,
    X > 3/5.

    Ans. = D.

  • Precalculus - ,

    Correction: The -5x^2 on the right side of the inequality sign should be
    -15x^2.

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