a) ( x-5)2 - x(x-6)= 5
=>x2-10x+25-x2+6x=5
=>25-4x=5
=>-4x=-20
=>x=5
b) (x - 7)2 - x(x-9)=14
=>x2-14x+49-x2+9x=14
=>49-5x=14
=>-5x=-35
=>x=7
c)đề chắc là thế này (x - 5)( x+5) - x(x -10) =5
=>x2-25-x2+10x=5
=>10x-25=5
=>10x=30
=>x=3
d)(x -6)(x-6) -x(x-4)=4
=>x2-12x+36-x2+4x=4
=>36-8x=4
=>-8x=-32
=>x=4
e) (x-3)2 -( x-2)(x+2)= -5
=>x2-6x+9-x2+4=-5
=>13-6x=-5
=>-6x=-18
=>x=3
g)(x -3)2 - x(x-2)= -5
=>x2-6x+9-x2+2x=-5
=>9-4x=-5
=>-4x=-14
=>x=7/2