Question

x-y=8
x.y=-9
Me ajudem​

Answer 1

{x-y=8 →x=y+8

{x.y=-9

(y+8)y=–9

y²+8y+9=0

∆=64–36

∆=28

y=(–8±2√7)/2

y'=(–8+2√7)/2 =–4+√7

y"=(–8–2√7)/2=–4–√7

Quando y=–4+√7

x–y=8

x–(–4+√7)=8

x+4–√7=8

x=8–4+√7

x=4+√7

Quando y=–4–√7

x–(–4–√7)=8

x+4+√7=8

x=8–4–√7

x=4–√7

S={(4+√7,–4+√7), (4–√7,–4–√7)}