2x-y=1
2x²-y²+x+y=-11
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y=2x-1
2x²-(2x-1)²+x+2x-1=-11
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y=2x-1
2x²-4x²+4x-1+x+2x-1=-11
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y=2x-1
-2x²+7x+9=0
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y=2x-1
2x²-7x-9=0, D=49+72=121,√D=√121=11
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y=2x-1
x1=(7+11)/4=9/2
x2=(7-11)/4=-1
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y1=9-1=8,y2=-3
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/x1,y1/=(9/2,8/ , /x2,y2/=/-1,-3/