1) 28-(1-4x-x²)=x²-6x+8.
28-1+4x+x²-x²+6x-8=0.
10x+19=0.
10x=-19.
x=-1,9.
2) 10-(2x²+5x)-(7x-2x²)=0.
10-2x²-5x-7x+2x²=0.
-12x+10=0.
-12x=-10.
x=10/12=⅚.
1) 28-(1-4x-x²)=x²-6x+8.
28-1+4x+x²-x²+6x-8=0.
10x+19=0.
10x=-19.
x=-1,9.
2) 10-(2x²+5x)-(7x-2x²)=0.
10-2x²-5x-7x+2x²=0.
-12x+10=0.
-12x=-10.
x=10/12=⅚.