
Originally Posted by
Viou
Hello
I want to solve a question, I don't understand why my answer is false so i think there might be an error in the order.
The quadratic function takes the value of 41 at x=-2 and the value of 20 at x=5. The function is minimalized at x=2.
I'm asked to give :
- the A,B,C of y=Ax^2+Bx+C
- the minimum value of this function, D
The appex have coordinates (2;D)
2=-B/2A
B=-4A
I then replaced B in
41=A(-2)^2 +B(-2)+C
20=A(5)^2 +B(5)+C
In the end I've got f(x)= (-3/7)x^2-(12/7)x+(275/7)
It can't be right because A can't be an negative number if the function has a minimum. Also in this case the appex is not in x=2 because D=239/7 (it's higher than f(-2)=20)
But when I calculate
f(-2)= (-3/7)(-2)^2-(12/7)(-2)+(275/7)
AND
f(5)=(-3/7)5^2-(12/7)5+(275/7)
It takes the value of 41 and 20.
Is it me confusing everything or there is really an error in the command?