1
{x²-11y=26
{x-y=4
y=x-4
x²-11(x-4)-26=0
x²-11x+18=0
x1+x2=11 U x1*x2=18
x1=2⇒y1=-2
x2=9⇒y2=5
(2;-2);(9;5)
2
{x+y=4
{x²-y²=32⇒(x-y)(x+y)=32⇒x-y=32:4⇒x-y=8
прибавим
2x=12
x=6
6+y=4
y=4-6
y=-2
(6;-2)
3
{y=x-5
{x²=10+y²
x²=10+(x-5)²
x²=10+x²-10x+25
10x=35
x=3,5
y=3,5-5
y=-1,5
4
{x+y=2⇒y=2-x
{x³+y³=26
x³+(2-x)³=26
x³+8-12x+6x²-x³-26=0
6x²-12x-18=0
x²-2x-3=0
x1+x2=2 U x1*x2=-3
x1=-1⇒y1=2+1=3
x2=3⇒y2=2-3=-1
(-1;3);(3;-1)