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Can anyone please explain how to solve the following inequality?

x(3x + 2) > (x + 2)^2

3 Answers

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  • 1 decade ago
    Favorite Answer

    Distribute the x on the left and square the right side. So then it would be

    3x^2 + 2x > x^2 + 4x + 4

    subtract x^2 and 2x from both sides

    2x^2 > 2x + 4

    factor a 2 from 2x + 4

    2x^2 > 2(x + 2)

    divide by 2 on both sides

    x^2 > x + 2

    subtract an x and a 2

    x^2 - x - 2 > 0

    factor

    (x-2)(x+1)>0

    x>2 or x>-1

    so I guess you could write it as -1<x>2

    hope I helped!!

  • 1 decade ago

    it is easy.

    to prove the inequality, simplify both these.

    x(3x + 2) > (x + 2)^2

    3x^2+2x > x^2 + 4 +4x

    2x^2 - 2x > 4

    2x(x-1)>4

    let x = 2

    both are equal.

    x = 3

    equation satisfies inequality.

    hence for every value of x above 2 , inequality occurs

  • M3
    Lv 7
    1 decade ago

    solve it as a quadratic first

    and then test the 3 parts that the answers can give

    by first testing the middle part.

    if it doen't fit the bill, the other 2 will

    the quadratic will yield the solution (-1,2)

    <------ | ------------- | -------->

    . . . .-1 . . . . . . . 2

    the middle part on testing doesn't fit, so

    ans: x < -1 or x > 2

    -----

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