Posted by Jayden Haddy on .
solve the following equation by completing the square
x(square) 13x + 21 = 0
Then x= or x=

maths 
Steve,
x^213x+21 = 0
x^213x+(13/2)^2 + 21  (13/2)^2 = 0
(x  13/2)^2  85/4 = 0
x  13/2)^2 = 85/4
x  13/2 = ±√85/2
x = (13±√85)/2