quadratic ques

Question

write the standard form of the quadratic function that has been reflected on the x-axis and stretched vertically bye a factor of 2 and has a vertex at (5,8)

Answer 1

y = x² is the parent function

 

Reflected across the x-axis:

 

     y = -x²

 

Stretched vertically by a factor of 2:

 

     y = -2x²

 

Has a vertex at (5,8):

 

     y = -2(x-5)² + 8

 

This is the vertex form. To put it into standard form, just FOIL it out and combine like-terms:

 

     y = -2x² + 20x - 50 + 8

     y = -2x² + 20x - 42