Y=x^2+3x+29 how do you complete the square

X^2 +3x +29 = 0
To complete the square:
Move "non-x" term to the right
x^2 +3x  = -29
Divide equation by coefficient of x^2
(the equation already had the x^2 coefficient as 1)
Take coefficient of x
divide it by 2
square it
add it to both sides of equation
3
3/2 = 1.5
1.5^2 = 2.25

x^2 +3x +2.25 = -29 +2.25
Taking square root of both sides
(x +1.5) = sq root( -26.75 )

square roots of negative numbers are complex (I don't know how to do that).

20000 as first it increases by 2500 then by 5000 so next it will increase by 10000