Question

Решите неравенство.а)15 - 3(1- х) < 2+ 7хб) - х"+3х -2< 0

Answer 1

a) 15 - 3(1-x) < 2 + 7x

15 - 3 + 3x <2 + 7x

4x > 10

x > 2.5

б) -x^2 + 3x -2 <0

-x^2 +3x - 2 = 0

D = (9 - 8) = 1

x1,2 = (-3 +- 1) /2

x1 = -1 ; x2 = -2

(x +1) (x+2) <0

 

x+1> 0          x+1 <0

x+1<0           x+1> 0

нет                x< -1

корней          x>-2

 

Ответ: (-2; -1)