If you complete the square on the equation \[x^2 + 10x = 9,\]you will get an equation of the form "$(x + r)^2 = c$". Enter this equation.
x^2 + 10x = 9
Take 1/2 of 10 = 5
Square this = 25
Add to both sides
x^2 + 10x + 25 = 9 + 25
x^2 + 10x + 25 = 34 factor the left side
( x + 5)^2 = 34