Решите неравенство 28(x^2+1)≤x+30

Question

Решите неравенство
28(x^2+1)≤x+30

Answer 1

28(х²+1) ≤ х+30
28х² + 28 ≤ х + 30
28х²+28-х-30≤0
28х²-х-2≤0
D = 1-4*28*(-2)=1+224=225=15²
х1=1+15/56=16/56=2/7
х2=1-15/56=-14/56=-2/8=-1/4
х€[1/4;2/7]

Answer 2

28x²-x-2≤0
D=1+224=225
x1=(1-15)/56=-1/4
x2=(1+15)/56=2/7
x∈[-1/4;2/7]