Question

X²-2x-5=0 решить в ответах а)-5, б) -2, в) 2, г) 5. Какой правильный?

Answer 1

Ответ: √6+1; -√6+1........

Answer 2

To find the correct solutions for the equation $x^2 - 2x - 5 = 0$, we can use the quadratic formula:

$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$

where $a$, $b$, and $c$ are the coefficients of the quadratic equation $ax^2 + bx + c = 0$.

In this case, the equation $x^2 - 2x - 5 = 0$ is in the form $ax^2 + bx + c = 0$ with $a = 1$, $b = -2$, and $c = -5$. Now we can substitute these values into the quadratic formula:

$x = \frac{-(-2) \pm \sqrt{(-2)^2 - 4 \cdot 1 \cdot (-5)}}{2 \cdot 1}$ $x = \frac{2 \pm \sqrt{4 + 20}}{2}$ $x = \frac{2 \pm \sqrt{24}}{2}$ $x = \frac{2 \pm 2\sqrt{6}}{2}$

Now, let's simplify and find the solutions:

a) $x = \frac{2 + 2\sqrt{6}}{2} = 1 + \sqrt{6} \approx 3.45$ б) $x = \frac{2 - 2\sqrt{6}}{2} = 1 - \sqrt{6} \approx -1.45$ в) $x = 2$ (one of the roots, which is not obtained from the quadratic formula) г) $x = 5$ (one of the roots, which is not obtained from the quadratic formula)

Out of the options provided:

a) $-5$ - Incorrect (the correct value is $1 + \sqrt{6}$) б) $-2$ - Incorrect (the correct value is $1 - \sqrt{6}$) в) $2$ - Correct (one of the roots obtained from the quadratic formula) г) $5$ - Correct (one of the roots obtained from the quadratic formula)

So, the correct answers are в) $2$ and г) $5$.