First divide everything by 2:x2 - 4x + 3.5 = 0Then divide number in front of the x by 2 and put it in a bracket squared + x. Then outside the bracket subtract the halved number squared. Keep the symbol the same, in this case the minus sign.(x-2)2-22+ 3.5 = 0(x-2)2 - 0.5 = 0(x-2)2 = 0.5x - 2 = +/- square root 0.5 x = 2 +/- square root 0.5