Answer:
b =-6
Step-by-step explanation:
y= 2x^2 +bx+8
Put this in vertex form
2( x^2 + b/2 ) +8
2 ( x^2 + b/2 + b^2/4) +8 - 2(b^2/4)
2 ( x+ b/2) ^2 +8-b^/2
The x coordinate of the vertex is -b/2
The x coordinate from the graph is 3
3 = -b/2
-6 =b
