Write x2+4x−15x^2 + 4x - 15x2+4x−15 in the form (x+a)2+b(x + a)^2 + b(x+a)2+b where a a\,a and b b\,b are integers.
Hence, or otherwise, write down the coordinates of the turning point of the graph of y=x2+4x−15y = x^2 + 4x - 15y=x2+4x−15
