3√a+5|b|=7
当|b|min=0时,3√amax=7 √amax=7/3 2√amax=14/3
smax=2√amax-3|b|min=14/3-0=14/3
当√amin=0时,5|b|max=7 |b|max=7/5 3|b|max=21/5
smin=2√amin-3|b|max=2*0-21/5=-21/5
因此s的取值范围:s=[-21/5,14/3]
3√a+5|b|=7
当|b|min=0时,3√amax=7 √amax=7/3 2√amax=14/3
smax=2√amax-3|b|min=14/3-0=14/3
当√amin=0时,5|b|max=7 |b|max=7/5 3|b|max=21/5
smin=2√amin-3|b|max=2*0-21/5=-21/5
因此s的取值范围:s=[-21/5,14/3]