If you mean what do you have to do to 2.102 to get 2102 you have to multiply it by 1000
2.102x1000=2102

the equation is a quadratic one, and it has a positive coefficient on the leading term, meaning, is opening upwards, so it has a "burrow" for the vertex.
the minimum or lowest point for a quadratic opening upwards is, well, the vertex point :), the "x" value is the year, the "y" or f(x) value is the population, we're asked for the year, or the x-coordinate of the vertex
well
2 3 5 7 11 13 are all prime numbers and good luck in life
Y=2 has a slope of M=0
y=x has a slope of M=1
x=6 has an undefined slope
y-3x=7 has a slope of M=3
y=-3x+2 has a slope of M=-3
x+y=1 has a slope of M=-1