1)x(0.25x-3)-(0.5x+1)(0.5x-1)=0
0.25x²-3x-0.25x²+1=0
-3x=-1
x=1/3
2)(1.2-x)(x+1.2)+1.8x+x²=0
1.44-x²+1.8x+x²=0
1.8x=-1.44
x=0.8
3)0.49x²-3x-(0.7x+2)(0.7x-2)=0
0.49x²-3x-0.49x²+4=0
3x=4
x=4/3
4)(1.6x+1)(1-1.6x)-64x(1-0.04x)=0
1-2.56x²-64x+2.56x²=0
64x=1
x=1/64
1)(7x-5)²+67x-49x²=-2
49x²-70x+25+67x-49x²+2=0
3x=27
x=9
2)196x²-(14x+3)²+80x=-5
196x²-196x²-84x-9+80x+5=0
-4x=4
x=-1