Question:

Who can help me solve these equations showing all the steps?

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x ^2 + x = 0

n ^2 = 5n

7x ^2 = 3x

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  1. x ^2 + x = 0

    x (x+1) = 0, so x = 0 or x = -1

    n^2 -5n = 0

    n(n-5) = 0, so n = 0 or n = 5

    7x^2 - 3x = 0

    x (7x -3) = 0, so x = 0 or 7x - 3 = 0 ie: x = 3/7

    x ^2 - 8x = 0

    x ( x -8 ) = 0, so x = 0 or x = 8


  2. PROBLEM 1:

    Factor out an x:

    x(x + 1) = 0

    If two things multiply to be zero, then one of them must be zero.

    x = 0

    or

    x + 1 = 0

    x = -1

    Answer:

    x = 0 or x = -1

    PROBLEM 2:

    Get everything on one side by subtracting 5n from both:

    n² - 5n = 0

    Factor out n:

    n(n - 5) = 0

    Again:

    n = 0

    or

    n - 5 = 0

    Answer:

    n = 0 or n = 5

    PROBLEM 3:

    7x² - 3x = 0

    x(7x - 3) = 0

    x = 0

    or

    7x - 3 = 0

    7x = 3

    x = 3/7

    Answer:

    x = 0 or x = 3/7

    PROBLEM 4:

    x² - 8x = 0

    x(x - 8) = 0

    x = 0

    or

    x - 8 = 0

    Answer:

    x = 0 or x = 8

  3. x^2 + x = 0   <==== factor:

    x(x + 1) = 0   <==== set factors equal to 0 and solve

    x = 0 or x = -1

    n^2 = 5n   <==== collect terms and put in standard form

    n^2 - 5n = 0   <==== factor and continue as above

    n(n - 5) = 0

    n = 0 or n = 5

    7x^2 = 3x    <==== same steps as previous problem

    7x^2 - 3x = 0

    x(7x - 3) = 0

    x = 0 or x = 3/7

    x^2 - 8x = 0

    x(x - 8) = 0

    x = 0 or x = 8


  4. Do your own homework!

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