[tex]\displaystyle\bf\\\left \{ {{y = {x}^{2} } \atop {y = 2x + 15 }} \right. \\ \\ {x}^{2} = 2x + 15 \\ {x}^{2} - 2x - 15 = 0 \\ po \: \: \: teoreme \: \: \: vieta \\ {x}^{2} + bx + c = 0\\ x_{1} + x_{2} = - b\\ x_{1} x_{2} = c \\ \\ x_{1} + x_{2} = 2 \\ x_{1} x_{2} = - 15\\ x_{1} = 5\\ x_{2} = - 3 \\ \\ y _{1}= {5}^{2} = 25 \\ y_{2} = ( - 3) {}^{2} = 9[/tex]
Ответ: Парабола и прямая пересекаются ровно в двух точках ( 5 ; 25 ) и ( - 3 ; 9 )
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[tex]\displaystyle\bf\\\left \{ {{y = {x}^{2} } \atop {y = 2x + 15 }} \right. \\ \\ {x}^{2} = 2x + 15 \\ {x}^{2} - 2x - 15 = 0 \\ po \: \: \: teoreme \: \: \: vieta \\ {x}^{2} + bx + c = 0\\ x_{1} + x_{2} = - b\\ x_{1} x_{2} = c \\ \\ x_{1} + x_{2} = 2 \\ x_{1} x_{2} = - 15\\ x_{1} = 5\\ x_{2} = - 3 \\ \\ y _{1}= {5}^{2} = 25 \\ y_{2} = ( - 3) {}^{2} = 9[/tex]
Ответ: Парабола и прямая пересекаются ровно в двух точках ( 5 ; 25 ) и ( - 3 ; 9 )