A particle is thrown from below the x-axis and follows a path given by y = 9x - x^2. At what points does it intercept the x-axis.

2 Answers | Add Yours

justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

The particle is thrown from below the x-axis and intercepts the x-axis on it way up and down. When it intercepts the x-axis the y-coordinate is 0.

To determine the points where it intercepts the x-axis solve 9x - x^2 = 0

9x - x^2 = 0

=> x(9 - x) = 0

=> x = 0 and x = 9

The particle intercepts the x-axis at the points (0,0) and (9, 0)

Sources:
malagala's profile pic

malagala | College Teacher | (Level 2) Adjunct Educator

Posted on

The path of the particle is given by, 

                   y = 9x - x^2 .....(1)

when the particle intercepts the x-axis the y cordinate of the particle must be zero. In orther words when the particle intercepts the x-axis the verticle distance of the particle from the x axis should be zero.

Hence,

                   y = 0 .....(2)

Substitute this value in the equation (1)

                   0 = 9x - x^2

                   0 = x(9-x)

in order to satisfy this conditin ,

                     x = 0 or (9-x) = 0

                     x = 0 or x = 9

Hence we have obtains two points where the particle intercepts the x axis.

those two points are, (0,0) and (9,0)

 

We’ve answered 318,957 questions. We can answer yours, too.

Ask a question