Question

Решите неравенства:
а)(x^2-25)*(x^2-x-30)≤0
б)(16x^4-x^2)(-x^2-10)≤0

Answer 1

a) (x²-25)(x²-x-30)≤0
x²-25=(x-5)(x+5)
x²-x-30=0   D=121
x₁=6   x₂=-5
(x-6)(x+5)=0   ⇒
(x-5)(x+5)(x-6)(x+5)≤0
(x-5)(x+5)²(x-6)≤0
-∞_____+____(-5)____+_____5____-_____6_____+_____+∞
x∈(-5)U(5;6).
b) (16x⁴-x²)(-x²-10)≤0
(16x⁴-x²)(x²+10)≥0
x²(16x²-1)(x²+10)≥0   
x²(4x-1)(4x+1)(x²+10)≥0
x²≥0    x²+10>0   ⇒
-∞_______+_______-1/4___-____(0)__-____1/4_______+______+∞
x∈(-1/4;1/4).