1
{xy=10
{x=2y+1
(2y+1)*y=10
2y²+y-10=0
D=1+80=81
y1=(-1-9)/4=-2,5⇒x1=-2,5*2+1=-5+1=-4
y2=(-1+9)/4=2⇒x2=2*2+1=4+1=5
(-4;-2,5);(5;2)
2
a){x²+y²=17
{x+4y=0⇒x=-4y
16y²+y²=17
17y²=17
y²=1
y1=-1⇒x1=-4*(-1)=4
y2=1⇒x2=-4*1=-4
(4;-1);(-4;1)
b){x+3y=11⇒x=11-3y
{2x+y²=14
2*(11-3y)+y²=14
y²-6y+8=0
y1+y2=6 U y1*y2=8
y1=2⇒x1=11-3*2=11-6=5
y2=4⇒x2=11-3*4=11-12=-1
(5;2);(-1;4)