Question

x²+x-72=0 2x²+5x-3=0​

Answer 1

Ответ:

Задание 1

${x}^{2} + x - 72 = 0 \\ d = 1 + 72 \times 4 = 1 + 288 = 289 \\ x1 = \frac{ - 1 + \sqrt{289} }{2} = \frac{ - 1 + 17}{2} = 8 \\ x2 = \frac{ - 1 + - \sqrt{289} }{2} = \frac{ - 1 - 17}{2} = - 9 \\ \\ otvet ..(x1 = 8)..(x2 = - 9)$

Задание 2

$2 {x}^{2} + 5x - 3 = 0 \\ d = 25 + 2 \times 3 \times 4 = 25 + 24 = 49 \\ x1 = \frac{ - 5 + \sqrt{49} }{2 \times 2} = \frac{ - 5 + 7}{4} = \frac{1}{2} = 0.5 \\ x2 = \frac{ - 5 - \sqrt{49} }{4} = \frac{ - 5 - 7}{4} = - 3 \\ \\ otvet..(x1 = 0.5)..(x2 = - 3)$

Answer 2

х² + х - 72 = 0

D = b² - 4ac = 1² - 4 · 1 · (-72) = 1 + 288 = 289

√D = √289 = ±17

х = (-b±√D)/2а

х₁ = (-1-17)/(2·1) = (-18)/2 = -9

х₂ = (-1+17)/(2·1) = 16/2 = 8

Ответ: (-9); 8.

- - - - - - - - - - - - - - - - - - - - -

2х² + 5х - 3 = 0

D = b² - 4ac = 5² - 4 · 2 · (-3) = 25 + 24 = 49

√D = √49 = ±7

х = (-b±√D)/2а

х₁ = (-5-7)/(2·2) = (-12)/4 = -3

х₂ = (-5+7)/(2·2) = 2/4 = 1/2 = 0,5

Ответ: (-3); 0,5.