Browse · MATH
Printjmc
algebra senior
Problem
A parabola with equation contains the points , , and . Find the value .
Solution
Since the points and have the same -value, the axis of symmetry of the parabola must be between these 2 points. The -value halfway between and is . Therefore the vertex of the parabola is equal to for some and the parabola may also be written as Now we substitute. The point gives or The point gives or Subtracting the second equation from the first gives so , giving .
Since and we know that and our parabola is In order to compute we can substitute and that gives
Since and we know that and our parabola is In order to compute we can substitute and that gives
Final answer
120