1)x^2+8x+16-(x^2+2x-2x-4)=0
x^2+8x+16-x^2-2x+2x+4=0
8x+20=0
8x=-20
x=-2,5
2)4x^2-20x+25-(4x^2+6x-6x-9)=0
4x^2-20x+25-4x^2-6x+6x+9=0
-20x+34=0
-20x=-34
x=1,7
3)9x^2-15x+15x-25-(9x^2-9x+1)=10
9x^2-15x+15x-25-9x^2+9x-1=10
9x=10+25+1
9x=36
x=4
4)2(4x^2+4x+1)-8(x^2-x+x-1)=34
8x^2+8x+2-8x^2+8x-8x+8=34
8x=34-2-8
8x=24
x=3