vertex form is y=a(x-h)^2+k
basically complete the square
isolate the x^2 and x term, then undistribute the -2
y=-2(x^2-8x)-37
take 1/2 of -8 and square it and add 0 to inside
y=-2(x^2-8+16-16)-37
complete the squaer
y=-2((x-4)^2-16)-37)
distribute the -16 to the -2
y=-2(x-4)^2+32-37
y=-2(x-4)^2-5