a, (x-1)^2 + (x+3)^2 = 2(x-2)(x+1) + 38
<=> x^2 -2x +1 + x^2 + 6x +9 = 2x^2 +2x -4x -4 +38
<=> x^2 -2x +x^2 +6x -2x^2 -2x +4x= -4 +38 -10
<=> 6x= 24
<=> x = 4
=> S={4}
b, 5(2x-3)-4(5x-7)= 19 -2(x+11)
<=> 10x -15 -20x +28 = 19-2x-22
<=> 10x -20x +2x = 19 -22 +15 -28
<=> -8x = -16
<=> x = 2
=> S={2}