=((x+5)+(x-5))((x+5)²-(x+5)(x-5)+(x-5)²)=x²(x²+10x+25-(x²-25)+x²-10x+25)=x²(2x²+50-x²+25)=x²(x²+75)=x⁴+75x²
12b+8-4b+6=0, b=0.8
9.6 + 8 - 3,2 + 6 = 20.4