Answer:
[-18, ∞]
Explanation:
Y=2x^2+12x
Case 1
a>0 then f(x)≥c−b*b/4a.
In fact for any y≥c−b/2a we have
So the range of f(x) is [c−(b* b) /4a, ∞)
Case 2
a<0 then f(x)≤c−b*b/4a and for any y<c−b/2a
So the range of f(x) is [−∞, c−(b* b) /4a]
So, for this, a=2>0, b=12 and c=0;
Applying case 1, because a=2
Range=[ c−(b* b) /4a, ∞]
=[0-(12*12)/(4*2), ∞]
=[0-144/8, ∞]
=[0-18, ∞]
=[-18, ∞]