Express 3x^2+18x-1 in the form a(x+b)^2 +c

3x^2+18x-1 Bracket out 3x^2+18x  Factorise by bringing out the common factor of 3 = 3(x^2+6x) Divide the x coefficient by 2  =  3(x^2+3x) And then remove the square on the x^2 variable and add a square to the outside of the bracket = 3(x+3)^2 Then subtract the square of the previously divided x coefficient .i.e. (3)^2        =   3((x+3)^2 - 9) - 1)  = 3(x+3)^2 -27 -1 = 3(x+3)^2 -28