Question

Решите систему уравнений 2х^2-7х-15=0

Answer 1

ответ:  $x_{1} = 5,\\x_{2} = - 1,5.$

$2x^2 - 7x - 15=0\\D = \sqrt{b^2 - 4ac} = \sqrt{(-7)^2 - 4*2*(-15)} = \sqrt{49 +120} = \sqrt{169} =13\\x_{1} =\frac{-b+D}{2a} = \frac{-(-7)+13}{2*2} = \frac{20}{4} = 5\\x_{2}= \frac{-b-D}{2a} = \frac{-(-7)-13}{2*2} = -\frac{6}{4} = -1,5$

Answer 2

X1 = - 1½;X2 = 5

Объяснение:

$2x {}^{2} - 7x - 15 = 0 \\ \\$

D = ( - 7 )² - 4 * 2 * ( - 15 ) = 49 + 120 = 169 D = 13

$x1 = \frac{7 - 13}{2 \times 2} \\ \\ x2 = \frac{7 + 13}{2 \times 2} \\ \\ x1 = - \frac{6}{4} = - 1 \frac{1}{2} \\ \\ x2 = 5$

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