Question 443087:  Can you help me solve this please 
There are 3 equations in turning point form.(vertex form) 
y=a(x-0)^2+300 The points on the graph are (0,300)(-122.5,0) and (122.5,0) 
y=a(x-122.5)^2+300 The points on the graph are (122.5,300)(245,0) and (0,0) 
y=a(x+122.5)^2-300 The points on the graph are (-122.5,300) (-245,0) and (0,0)  
Can you please show me how to find the "a". 
i Know the answer is -0.02 for all of them but i cant figure out how? 
Your help is appreciated. 
thanks 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! There are 3 equations in turning point form.(vertex form) 
y=a(x-0)^2+300 The points on the graph are (0,300)(-122.5,0) and (122.5,0) 
Let x = 122.5 and y = 0 ; then solve for "a". 
I get a = -0.02 
--- 
y=a(x-122.5)^2+300 The points on the graph are (122.5,300)(245,0) and (0,0) 
Let x = 0 and y = 0 ; then solve for "a". 
I get a = -0.02 
---- 
y=a(x+122.5)^2-300 The points on the graph are (-122.5,300) (-245,0) and (0,0) 
Let x= 0 and y = 0 ; then solve for "a". 
I get a = +0.02 
------------------------------------------------ 
--- 
Cheers, 
Stan H. 
==================  
 
  | 
 
  
 
 |   
 
 |