How do you solve x^2+16x=260

My mind has gone blank I just completely forget. Please show me step by step.
Thank you! :)

x^2 + 16x = 260
x^2 + 16x - 260 = 0
x^2 + 26x - 10x - 260 = 0
x(x + 26) - 10(x + 26) = 0
(x + 26)(x - 10) = 0
The solutions x = -26 and x = 10

subtract the 260 over so its x^2 + 16x - 260 = 0. Then plug it into the quadratic formula: (-b +/- sqrt(b^2-4ac))/(2a) where a=1 b=16 and c = -260. You should get x = 10 and x = -26

X^2+ 16x = 260

take Lhs (X+ 8)^2=260+64
(X+8)^2= 324

Therefore x+8= Sqrt (324)= +18 0r - 18
x= - 8 + 18= 10 0r X= - 18- 8 = -26

Therefore Ans X= 10 0r - 26

x^2+16x=260
x^2 +16x -260 = 0
(x+26)(x-10) = 0
x = -26 ; 10