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anonymous

  • one year ago

find the x-intercepts of the parabola with vertex (4,-1) and y-intercept (0,15) write your answer in this form:(x1,y1),(x2,y2) f necessary, round to the nearest Hundredth

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  1. campbell_st
    • one year ago
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    well the vertex form of a parabola is \[y=a(x - h)^2 + k\] where (h, k) is the vertex. so substitute you vertex values, h = 4 and k = -1 into the equation. tThe y-intercept is on the parabola... so to find the value of a you need to substitute x = 0 and y = 15 and solve for a. then you can rewrite the equation of the parabola in standard form that's the 1st part hope it makes sense

  2. campbell_st
    • one year ago
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    once you have the equation in standard form you may need to use the general quadratic formula for the x intercepts

  3. anonymous
    • one year ago
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    soo would it be y=x^2-8x+15

  4. campbell_st
    • one year ago
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    that's the correct equation... and the equation can be factored.

  5. anonymous
    • one year ago
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    its wrong

  6. campbell_st
    • one year ago
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    so what did you get for the x-intercepts

  7. anonymous
    • one year ago
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    -4

  8. campbell_st
    • one year ago
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    the equation is \[y=x^2 - 8x + 15~~~~then~~~~y=(x -5)(x-3)\]

  9. campbell_st
    • one year ago
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    so the intercepts are

  10. campbell_st
    • one year ago
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    where y = 0 so solve x - 5 = 0 and x - 3 = 0

  11. anonymous
    • one year ago
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    am confused

  12. campbell_st
    • one year ago
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    ok.... so the x-intercepts these are points on the x-axis so y = 0 if you have a parabola to find the x-intercepts let y = 0 and solve for x so \[0 = x^2 - 8x + 15~~~or~~~0 =(x -5)(x -3)\] if either of the factors (x -5) or (x -3) are equal to zero the equation is equal to zero... so then you need to let the factors equal zero and solve for x so solve x - 5 = 0 and x - 3 = 0 what would you have...?

  13. campbell_st
    • one year ago
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    the other thing to think about is that the x-intercepts are the same distance from the x value in the vertex .

  14. anonymous
    • one year ago
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    am go fail this test

  15. campbell_st
    • one year ago
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    so if you the solve the 2 equations what do you get x - 5 = 0 and x - 3 = 0

  16. campbell_st
    • one year ago
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    these values are the x-intercepts

  17. anonymous
    • one year ago
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    x=5,3

  18. campbell_st
    • one year ago
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    correct so the intercepts are at (3,0) and (5, 0) the vertex has an x value of x = 4... the intercepts are the same distance from this value

  19. anonymous
    • one year ago
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    thank u soo much

  20. campbell_st
    • one year ago
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    yw

  21. anonymous
    • one year ago
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    it was wrong

  22. campbell_st
    • one year ago
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    so did you write the intercepts as (3, 0) and (5, 0)..?

  23. anonymous
    • one year ago
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    yea

  24. campbell_st
    • one year ago
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    here is a graph of the parabola you gave... and it meets all the conditions... can you check the vertex is (4, -1) and y-intercept is y = 15 or (0. 15)

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