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2014-05-04T21:14:02+03:00
1.   7x-3y=26
2x+2y=16     2x=16-2y   x=8-y

7(8-y)-3y=26  56-7y-3y=26    -10y=-30  y=3 
x=8-3=5


2.   (2x+1)²-4(x+3)(x-5)=5(x+3)+4
4x²+4x+1-4(x²-2x-15)=5x+15+4
12x+61=5x+19
7x=-42
x=6

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