40^4 =5^4 *8^4 =5^4 *(2^3)^4 =5^4 *2^12
(5^4 *2^12) /(5^2 *2^11) +(0.2^6 *5^6) =(5^2 *2) +(0.2*5)^6 =25*2 +1 =51
Если я не ошибаюсь:
5) D=1+48=49
x1=1-√49/2=1-7/2=-6/2=-3
x2=1+7/2=8/2=4
6) D=9+16=25
x1=3-5/2=-1
x2=3+5/2=4
7) D=1+24=25
x1=1-5/2=-2
x2=1+5/2=3
8) D=4+60=64
x1=-2-8/2=-5
x2=-2+8/2=3