-3x²-18x-31 group x terms (-3x²-18x)-31 undistribute the -3 -3(x²+6x)-31 take 1/2 of the linear coefient (6) and squaer it 6/2=3, 3²=9 add positive and negative of it inside parenthasees -3(x²+6x+9-9)-31 complete the square -3((x+3)²-9)-31 expand -3(x+3)²+27-31 -3(x+3)²-4 is vertex form
