1) = x²+2x-(x²-9)=13
x²+2x-x²+9=13
2x+9=13
2x=13-9
2x=4 |:2
x=2
2) = 4x²-4x-(4x²-25)=1
4x²-4x-4x²+25=1
-4x+25=1
-4x=1-25
-4x=-24 | : -4
x=6
3) = x²+4x-3x-12-6x+4=x²-8x+16
4x-3x-12-6x+4=-8x+16
-5x+8= -8x+16
-5x+8x=16+8
3x=24 | :3
x=8
4) = x²+2x-5x-10-12x+9=x²-10x+25
2x-5x-10-12x+9=10x+25
-15x-1= -10x+25
-15x+10x=25+1
-5x=26 | : -5
x= -26 = -5 1
5 5