Question

Решите пример
2x-tex]5x^{2}[/tex]+7=0

Answer 1

0.2*0.2=0.4 2.5*0.4*10^-3=1×10^-3

Answer 2

$2x-5x^2+7 = 0\\\\5x^2 -2x - 7 = 0\\\\a = 5\\b=-2\\c = -7\\D = (-2)^2 - 4 * 2 * (-7) = 4 + 32 = 36\\\\x_1 = \frac{2-\sqrt{36} }{2*2} = \frac{2-6}{4} = \frac{-4}{4} = -1\\\\x_2 = \frac{2+\sqrt{36} }{2*2} = \frac{2+6}{4} = \frac{8}{4} = 2$

Использованные формулы:

Для $ax^2 + bx + c = 0$:

$x_1 = \frac{-b-\sqrt{D} }{2a} \\x_2 = \frac{-b+\sqrt{D} }{2a}$

$D = b^2 - 4ac$