Решите неравенство: (√21 - 5) (5x - 1,5) > 0

21-5=16 а корень из 16 равно 4

4 (5 х-1.5) >0

20 х-6>0

20x>6

x>20/6

х^ (2) - 0,5x-5<0

x2 - 0.5x - 5 = 0

D = b2 - 4ac

D = 0.25 + 20 = 20.25 = (√20.25) ^2

x1,2 = - b ± √D/2a

x1 = 0.5 + √20.25/2

x2 = 0.5 - √20.25/2

Ответ: x1 = 0.5 + √20.25/2; x2 = 0.5 - √20.25/2

x2 - 0.5x - 5 = a (x-x1) (x+x2) = (x-0.5 + √20.25/2) (x+0.5 - √20.25/2)

(x-0.5 + √20.25/2) (x+0.5 - √20.25/2) <0