b, 2x(x-5)-x(3+2x)=0
<=> 2x^2 -10x -3x -2x^2= 0
<=> -13x=0
<=> x=0

2x ( x - 5 ) - x ( 3 + 2x) = 0 
2x^2 - 10x - 3x - 2x^2 = 0
-13x = 0
x = 0

( x - 1 ) ^ 2 - 2( 3 + x^2 ) - x^2 = 0 
x^2 - 2x + 1 - 6 - 2x^2 - x^2 = 0
- 2x - 5 - 2x^2 = 0

 ( 3x - 1 ) ( 2 + x ) = 3 ( x^2 - 2 ) 
5x + 3x^2 - 2 = 3x^2 - 6
5x + 3x^2 - 2 - 3x^2 + 6 = 0
5x + 4 = 0
x = -4/5