How to solve this problem of finding the Arch support?












0












$begingroup$


I am self-studying precalculus on my own. This is a problem from Ron Larson's precalculus 10e




The arch support of a bridge is
modeled by
$y = −0.0012x^2+
300$
, where x and y are
measured in feet and the x-axis represents the ground.



(a) Use a graphing utility to graph the equation.



(b) Find one x-intercept of the graph. Explain how to
use the intercept and the symmetry of the graph to
find the width of the arch support.




For the first question (a) I graphed it on desmos



And for the second problem my approach was to use the distance formula and the answer was 1000feet. Since I am doing everything all on my own I have no way of knowing if my answer is correct or not.



Can anybody help me with this please?










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    0












    $begingroup$


    I am self-studying precalculus on my own. This is a problem from Ron Larson's precalculus 10e




    The arch support of a bridge is
    modeled by
    $y = −0.0012x^2+
    300$
    , where x and y are
    measured in feet and the x-axis represents the ground.



    (a) Use a graphing utility to graph the equation.



    (b) Find one x-intercept of the graph. Explain how to
    use the intercept and the symmetry of the graph to
    find the width of the arch support.




    For the first question (a) I graphed it on desmos



    And for the second problem my approach was to use the distance formula and the answer was 1000feet. Since I am doing everything all on my own I have no way of knowing if my answer is correct or not.



    Can anybody help me with this please?










    share|cite|improve this question











    $endgroup$















      0












      0








      0


      1



      $begingroup$


      I am self-studying precalculus on my own. This is a problem from Ron Larson's precalculus 10e




      The arch support of a bridge is
      modeled by
      $y = −0.0012x^2+
      300$
      , where x and y are
      measured in feet and the x-axis represents the ground.



      (a) Use a graphing utility to graph the equation.



      (b) Find one x-intercept of the graph. Explain how to
      use the intercept and the symmetry of the graph to
      find the width of the arch support.




      For the first question (a) I graphed it on desmos



      And for the second problem my approach was to use the distance formula and the answer was 1000feet. Since I am doing everything all on my own I have no way of knowing if my answer is correct or not.



      Can anybody help me with this please?










      share|cite|improve this question











      $endgroup$




      I am self-studying precalculus on my own. This is a problem from Ron Larson's precalculus 10e




      The arch support of a bridge is
      modeled by
      $y = −0.0012x^2+
      300$
      , where x and y are
      measured in feet and the x-axis represents the ground.



      (a) Use a graphing utility to graph the equation.



      (b) Find one x-intercept of the graph. Explain how to
      use the intercept and the symmetry of the graph to
      find the width of the arch support.




      For the first question (a) I graphed it on desmos



      And for the second problem my approach was to use the distance formula and the answer was 1000feet. Since I am doing everything all on my own I have no way of knowing if my answer is correct or not.



      Can anybody help me with this please?







      algebra-precalculus






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      edited Jan 12 at 7:59









      Andrei

      13.7k21230




      13.7k21230










      asked Jan 12 at 7:37









      user633979user633979

      32




      32






















          1 Answer
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          $begingroup$

          Your answer is correct. Here is an example of how I would solve the problem.



          We begin by finding the $x$-intercepts, using the fact that the $x$-intercepts are the points where $y = 0$
          begin{align}
          -0.0012x^2 + 300 = y &= 0 \
          0.0012x^2 &= 300 \
          x^2 = frac{300}{0.0012} &= 250000
          end{align}

          One solution to this equation is $x = sqrt{250000} = 500$, and since we can see that the graph is symmetric around the $y$-axis, we must have that $x = -sqrt{250000} = -500$ is also a solution. So we get the width of the arch support to be the difference $500 - (-500) = 1000$ feet between these two points, just as you got.






          share|cite|improve this answer









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            1 Answer
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            1












            $begingroup$

            Your answer is correct. Here is an example of how I would solve the problem.



            We begin by finding the $x$-intercepts, using the fact that the $x$-intercepts are the points where $y = 0$
            begin{align}
            -0.0012x^2 + 300 = y &= 0 \
            0.0012x^2 &= 300 \
            x^2 = frac{300}{0.0012} &= 250000
            end{align}

            One solution to this equation is $x = sqrt{250000} = 500$, and since we can see that the graph is symmetric around the $y$-axis, we must have that $x = -sqrt{250000} = -500$ is also a solution. So we get the width of the arch support to be the difference $500 - (-500) = 1000$ feet between these two points, just as you got.






            share|cite|improve this answer









            $endgroup$


















              1












              $begingroup$

              Your answer is correct. Here is an example of how I would solve the problem.



              We begin by finding the $x$-intercepts, using the fact that the $x$-intercepts are the points where $y = 0$
              begin{align}
              -0.0012x^2 + 300 = y &= 0 \
              0.0012x^2 &= 300 \
              x^2 = frac{300}{0.0012} &= 250000
              end{align}

              One solution to this equation is $x = sqrt{250000} = 500$, and since we can see that the graph is symmetric around the $y$-axis, we must have that $x = -sqrt{250000} = -500$ is also a solution. So we get the width of the arch support to be the difference $500 - (-500) = 1000$ feet between these two points, just as you got.






              share|cite|improve this answer









              $endgroup$
















                1












                1








                1





                $begingroup$

                Your answer is correct. Here is an example of how I would solve the problem.



                We begin by finding the $x$-intercepts, using the fact that the $x$-intercepts are the points where $y = 0$
                begin{align}
                -0.0012x^2 + 300 = y &= 0 \
                0.0012x^2 &= 300 \
                x^2 = frac{300}{0.0012} &= 250000
                end{align}

                One solution to this equation is $x = sqrt{250000} = 500$, and since we can see that the graph is symmetric around the $y$-axis, we must have that $x = -sqrt{250000} = -500$ is also a solution. So we get the width of the arch support to be the difference $500 - (-500) = 1000$ feet between these two points, just as you got.






                share|cite|improve this answer









                $endgroup$



                Your answer is correct. Here is an example of how I would solve the problem.



                We begin by finding the $x$-intercepts, using the fact that the $x$-intercepts are the points where $y = 0$
                begin{align}
                -0.0012x^2 + 300 = y &= 0 \
                0.0012x^2 &= 300 \
                x^2 = frac{300}{0.0012} &= 250000
                end{align}

                One solution to this equation is $x = sqrt{250000} = 500$, and since we can see that the graph is symmetric around the $y$-axis, we must have that $x = -sqrt{250000} = -500$ is also a solution. So we get the width of the arch support to be the difference $500 - (-500) = 1000$ feet between these two points, just as you got.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 12 at 7:58









                nesHannesHan

                1785




                1785






























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