5x^2-16x+3=0
D=(-16)^2-4*5*3=sqrt 196=14
x1=16+14/2*5=3
x2=16-14/2*5=2/10=0,2
x^2+2x-80=0
D=2^2-4*1*(-80)=sqrt 324=18
x1=-2+18/2=8
x2=-2-18/2=-10
x^2-22x-23=0
D=(-22)^2-4*1*(-23)=sqrt 576 =24
x1=22+24/2=23
x2=22-24/2=-1
1
(x-4y-4x+y)(x-4y+4x-y)=(-3x-3y)((5x-5y)=-15(x+y)(x-y)=-15(x²-y²)
x=1 1/3 y=-2
-15(16/9-4)=-15*(-20/9)=100/3=33 1/3
2
x^4-2x²+1-x^4+25+32-16x+2x²=-16x+58
x=-0,25
-16*(-1/4)+58=4+58=62
3
a²+12a+36-a²+4=12a+40
a=1 3/4
12*7/4+40=21+40=61
4
x^8-9-x^8+10x^4-25=10x^4-34
x=3
10*81-34=810-34=776