Question

设集合A={x|-2≤x≤5},B={x| |x-1|≤a},若B包含A,求实数a的取值范围

是 若B包含于A

Answer 1

A={x|-2≤x≤5}
B={x| |x-1|≤a}
= { x| -a+1≤x≤a+1 }

if B is subset of A, then

-a+1≥ -2 and a+1≤5
=> a≤3 and a≤4
=> a≤3 #