Question

find x if (x-1)(x+1)(x+2)(x-2)≤0

Answer 1

|x−1||x−2|≤|x−1|=0≤(x−1)2(x−2)2≤(x−1)2(x−1)=2((x−2)2–1)≤0(x−3)(x−1)≤0|=x−1||x−2|≤|x−1|=0≤(x−1)2(x−2)2≤(x−1)2(x−1)=2((x−2)2–1)≤0(x−3)(x−1)≤0

so ,x∈[1;3]