We can work out the first three terms of this quadratic equation with substitution.
The first term of this sequence is where n=1, we can substitute 1 in for n
y=1^2+2(1)-4
y=1+2-4
y=-1
We can do this for the next two terms as well
y=2^2+2(2)-4
y=4+4-4
y=4
For the last term:
y=3^2+2(3)-4
y=9+6-4
y=11
