1)x+7=3
x=-4
2)x-3=3
x=6
3)y-3=5
y=8
4)y+2=1
y=-1
1) (100-10) :6=90:6=15
2) (780-10):14=770:14=55
2x²-5x+1=0
D=25-8=17
x1 = (5+√17)/4
x2 = (5-√17)/4
x1^2 = (25+10√17+17)/16 = (42+10√17)/16
x2^2 = (25-10√17+17)/16 = (42-10√17)/16
x1^2 + x2^2 = (42+10√17+42-10√17)/16 = 84/16 = 5,25
Ответ: 5,25