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{x(x+y)+y2=4x−1(1)x(x+y)2−2y2=7x+2(2)
Từ pt (1) ta thay neu x=0 thi (1)<=>y2=−1=>hpt vo nghiem
Ta chia 2 ve cua hpt cho x≠0 ta dc hpt
{x+y+y2x=4−1x(x+y)2−2y2x=7+2x
<=>{(x+y)+y2x+1x=4(x+y)2−2(y2x+1x)=7(*)
Đặt a=x+y
b=y2x+1x
hpt(*) tro thanh
{a+b=4a2−2b=7
<=>{b=4−aa2+2a−15=0
<=>{b=4−aa=3hoaca=−5
<=>{a=3b=1 v {a=−5b=9
.{a=3b=1
<=>{x+y=3y2+1x=1
<=>{x=3−yy2+y−2=0
<=>{x=3−yy=1hoacy=−2
<=>{x=2y=1 v {x=5y=−2
.{a=−5b=9
<=>{x+y=−5y2+1x=9
<=>{x=−5−yy2+9y+46=0(hptVN)
Vay S={(2;1);(5;-2)}
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