Question

Решить уравнения

x2+x-6=0
5x2+3x-8=0
5x2+14x-3=0

Answer 1

$1) {x}^{2} + x - 6 = 0 \ x1x2 = - 6 \ x1 + x2 = - 1 \ x1 = - 3 \ x2 = 2 \ \ 2)5 {x}^{2} + 3x - 8 = 0 \ d = 9 + 160 = 169 \ x1 = frac{ - 3 + 13}{10} = 1 \ x2 = - frac{ - 3 - 13}{10} = - 1.6 \ \ 3)5 {x}^{2} + 14x - 3 = 0 \ d = 196 + 60 = 256 \ x1 = frac{ - 14 + 16}{10} = 0.2 \ x2 = frac{ - 14 - 16}{10} = - 3$

Answer 2

У тебя в последнем -30 / 10 = -2....

Answer 3

Спасибо)

Answer 4

#1

По Виету:

$x_1 + x_2 = -1, , x_1 x_2 = -6 Rightarrow x_1 = -3, x_2 = 2$

Через дискриминант:

$D = 1 - 4 cdot (-6) = 25 \ x_1 = frac{-1 - 5}{2} = -3, , x_2 = frac{-1 + 5}{2} = 2$

#2

По Виету:

$5x^2 + 3x - 8 = 0 Leftrightarrow x^2 + frac{3}{5}x - frac{8}{5}$

$x_1 + x_2 = -frac{3}{5}, , x_1 x_2 = -frac{8}{5} Rightarrow x_1 = 1, , x_2 = -frac{8}{5}$

Через дискриминант:

$D = 9 - 4 cdot 5 cdot (-8) = 169 \ x_1 = frac{-3 - 13}{10} = -frac{8}{5}, , x_2 = frac{-3 + 13}{10} = 1$

#3

Через дискриминант:

$D = 14^2 - 4 cdot 5 cdot (-3) = 256 \ x_1 = frac{-14 - 16}{10} = -3, , x_2 = frac{-14 + 16}{10} = frac{1}{5}$

Answer 5

D₁ =D/4 =7² -5*(-3) = 8² ; x₁ , ₂ =(-7 ± 8) /5