Answer:
The +1 in f(x) is the y intercept
The +1 in g(x) is the y coordinate of the vertex
Explanation:
For f(x), plugging in x = 0 leads to
f(x) = 2x^2+5x+1
f(0) = 2(0)^2+5(0)+1
f(0) = 1
Showing that (0,1) is the y intercept of f(x).
The same is not true for g(x)
g(x) = 2(x+5)^2+1
g(0) = 2(0+5)^2+1
g(0) = 51
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The +1 for g(x) represents the y coordinate of the vertex. Recall that vertex form in general is
y = a(x-h)^2+k
with (h,k) being the vertex. This means we can quickly spot the vertex for g(x) without having to graph. The same cannot be said for f(x) as we need to complete the square to get f(x) into vertex form. Currently, f(x) is in standard form.