4a(a-2)-(a-4)^2=(4a-8)*a-(a-4)^2=4a^2-8a-(a-4)^2=4a^2-8a-(a^2-8a+16)=4a^2-8a-a^2+8a-16=3a^2-8a+8a-16=3a^2-16
25a^2-(a+3)^2=25a^2-(a^2+6a+9)=25a^2-a^2-6a-9=24a^2-6a-9
D=(-6)^2-4*24*(-9)=36+864=900
a1=36/48=0.75a2=-24/48=-0.5
4a(a-2)-(a-4)^2=(4a-8)*a-(a-4)^2=4a^2-8a-(a-4)^2=4a^2-8a-(a^2-8a+16)=4a^2-8a-a^2+8a-16=3a^2-8a+8a-16=3a^2-16
25a^2-(a+3)^2=25a^2-(a^2+6a+9)=25a^2-a^2-6a-9=24a^2-6a-9
D=(-6)^2-4*24*(-9)=36+864=900
a1=36/48=0.75
a2=-24/48=-0.5