1)
x+y=3
(x-y)²-1=0
x=3-y
(3-y-y)²-1=0
(3-2y)²-1=0
9-12y+4y²-1=0
4y²-12y+8=0
D=144-128=16
y1=12+4/8 = 16/8= 2
y2=12-4/8= 8/8=1
x1=3-2=1
x2=3-1=2
Ответ: (1;2) ; (2;1)
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2)
x+y=3
x=3-y
3^3-y + 3^y=12
27/3^y + 3^y=12
3^y=t
27/t+t=12
27+t²-12t=0
D=144-108=36
t1=12+6/2=18/2=9
t2=12-6/2=6/2=3
3^y=9
3^y=3²
y1=2
3^y=3
y2=1
x1=3-1=2
x2=3-1=2
Ответ: (1;2) ; (2;1)