∵(log10x−1)(ex−3)≤0, which is possible in following two cases.
Case 1:log10x−1≥0 & ex−3<0
⇒log10x≥1 & ex<3
⇒x≥10 & x<ln3
∴x∈ϕ
Case 2:log10x−1≤0 & ex−3>0
⇒log10x≤1 & ex>3
⇒x≤10 & x>ln3
∴x∈(ln3,10]
And 1<ln3<2∴2≤[x]≤10
[x]min=2 & [x]max=10∴difference=10−2=8.