1. QUADRATIC FUNCTION Given a Function y = 2x2 -6x -8 in domain
D= { x|-3 ≤ x ≤ 6}, Draw the graph of that function!
Solution :
The Intercepts
i. X- Intercepts ,Y=0, so 2x2 -6x -8 =0
x2- 3x -4 =0 →(x-4)(x+1)=0
the x-intercepts are x=4 and x=-1
then A (4,0) and B( -1,0)
ii. Y- Intercepts, x=0, y = 2x2 -6x -8, y = =-8
The intercepts is y =-8 , the C = ( 0,-8 )

2. Next b. The axis of parabola x = -b/2a = -(-6) /2.2 = 3/2
c. The Vertex V (x,y) , V ( -b/2a, -D/-4a)
x = -b/2a = 3/2
y = -D/4a = -(b2-4ac)/4a = -(36+64)/4.2
= ½
V ( 3/2 , -12 ½ )
V is minimum point because a= 2 (a>0)
so parabola is Upward

3. Next The Conclusion : X – intercepts A ( 4,0), B (-1,0)
d. The point which satisfy the function
The Conclusion :
X – intercepts A ( 4,0), B (-1,0)
y – intercepts C ( 0,-8)
Axis parabola x = 3/2
Vertex D ( 3/2, -12 ½ ) x -3 -2 -1 1 2 3 4 5 6 y 28 12 -8
-12

4. The Graph

5. About The Graph The Parabola Y= ax2+bx+c
Upward or downward, Depend on the
value of a
If a> and a<0

6. About The Graph… Vertex When We called Maximum or Minimum ?
Maximum Minimum
Downward Upward
a< a>0

7. Resume About the Graph….

8. Resume about the graph…
Definitif Negatif