Question

Помогите с уравнением ​

Answer 1

Ответ:

$3x^{2} + 5x + c = 0 \\ 3 \times ( { - 2})^{2} + 5 \times ( - 2) + c = 0 \\ 3 \times 4 - 10 + c = 0 \\ 12 - 10 + c = 0 \\ 2 + c = 0 \\ c = - 2$

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$3x^{2} + 5x + c = 0$

При с=-2

$3x^{2} + 5x + (-2) = 0$

а=3, b=5, с=-2

D=b²-4ac

D=25-4*3*(-2)=25+24=49=7²

$x_{1}=\frac{-5+7}{2*3}=\frac{2}{6}=\frac{1}{3}$

$x_{2}=\frac{-5-7}{2*3}=\frac{-12}{6} =-2$