Question

X^2-10x+21больше0решите плз

Answer 1

X² -10x+21>0

x²-3x-7x+21>0

x(x-3)-7(x-3)>0

(x-3)(x-7)>0

{x-3>0
{x-7>0
{x-3<0
{x-7<0


{x>3
{x>7
{x<3
{x<7

ответ x∈ (-∞; 3) U (7; +∞)

Answer 2

x² - 10x + 21 > 0

D = 100 - 84 = 16

x₁ = (10-4)/2 = 3

x₂ = (10+4)/2 = 7

x ∈ (-∞; 3) U (7; +∞)