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[tex]\displaystyle\bf\\\frac{x^{2}+3x }{2} =\frac{x+7}{4} \\\\\\\frac{x^{2}+3x }{2} \cdot4=\frac{x+7}{4}\cdot 4\\\\2\cdot(x^{2} +3x)=x+7\\\\2x^{2} +6x-x-7=0\\\\2x^{2} +5x-7=0\\\\D=5^{2} -4\cdot 2\cdot(-7)=25+56=81=9^{2} \\\\\\x_{1} =\frac{-5-9}{4} =-3,5\\\\\\x_{2} =\frac{-5+9}{4} =1\\\\\\Otvet: \ -3,5 \ ; \ 1[/tex]