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4 March, 02:08

Will mark brainliest if right and you show your work!

Factor completely

x^2+3x-40

Also can you use Desmos on this question?

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Answers (1)
  1. 4 March, 03:29
    0
    (x - 5) (x + 8)

    Step-by-step explanation:

    Your equation is: x² + 3x - 40

    1. Factor the quadratic

    (a) Find two numbers that multiply to give - 40 and add to give 3.

    List the positive factors of 40: 1, 2, 4, 5, 8, 10, 20, 40

    One of the numbers must be negative. Start with the numbers near the middle of the list.

    By trial and error, you will find that + 8 and - 5 work:

    -5 * 8 = - 40 and - 5+8 = 3

    (b) Rewrite 3x as - 5x + 8x

    x² - 5x + 8x - 40

    (c) Factor the first two and the last two terms

    x (x - 5) + 8 (x - 5)

    (d) Separate the common factor

    x² + 3x - 40 = (x - 5) (x + 8)

    2. Using Desmos

    You can plot the equation with Desmos.

    You get a parabola with x-intercepts at x = - 8 and x = 5.

    These are the solutions to

    x + 8 = 0 and x - 5 = 0, so

    x² + 3x - 40 = (x + 8) (x - 5)
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