SOLUTION: What are the $x$-coordinate(s) of all point(s) where the parabola $y = f(x)$ intersects the line $y = 0$? f(x) = 2x^2 - 13x + 20 - 5x^2 + 19x + 7. Your answer shoul

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: What are the $x$-coordinate(s) of all point(s) where the parabola $y = f(x)$ intersects the line $y = 0$? f(x) = 2x^2 - 13x + 20 - 5x^2 + 19x + 7. Your answer shoul      Log On


   



Question 1209639: What are the $x$-coordinate(s) of all point(s) where the parabola $y = f(x)$ intersects the line $y = 0$?

f(x) = 2x^2 - 13x + 20 - 5x^2 + 19x + 7.

Your answer should be a list of numbers and should not include variable names, nor should it include $y$-coordinates.

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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What are the x-coordinate(s) of all point(s) where the parabola y = f(x) intersects the line y = 0?

f(x) = 2x^2 - 13x + 20 - 5x^2 + 19x + 7.

Your answer should be a list of numbers and should not include variable names, nor should it include $y$-coordinates.
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(1)  Simplify  f(x) = 2x^2 - 13x + 20 - 5x^2 + 19x + 7 = -3x^2 + 6x + 27.



(2)  The intersection points of the parabola with the line y = 0

     are the points on x-axis where  -3x^2 + 6x + 27 = 0.

     In Algebra language, these points are called the roots of the equation

          -3x^2 + 6x + 27 = 0.

     In other terminology, these points are called  x-interception points.



(3)  So, your task is to solve this equation

          -3x^2 + 6x + 27 = 0.


     To simplify, divide both side by the common factor -3.  You will get an EQUIVALENT equation

           x^2 - 2x - 9 = 0.


     Apply the quadratic formula

           x%5B1%2C2%5D = %282+%2B-+sqrt%28%28-2%29%5E2+-+4%2A1%2A%28-9%29%29%29%2F2 = %282+%2B-+sqrt%2840%29%29%2F2 = 1+%2B-+sqrt%2810%29.


(4)  So, the roots of the given equation are  

         x%5B1%5D= 1-sqrt%2810%29 = -2.162 (rounded)  and  x%5B2%5D= 1%2Bsqrt%2810%29 = 4.162 (rounded).


     They are x-coordinates of the intersection points.

Solved, with all necessary explanations.