+(-3): plus or minus 3 (-3)-|+(-3)|: the reciprocal of the absolute value of plus or minus 3 (-3).

│-3.5│ is 3.5, because it is an absolute value, so it must be positive, with a negative sign in front, so it is -3.5.

-(+7) is -7, omitting the plus sign inside.

brief introduction

Positive number is a mathematical term. Numbers greater than 0 are called positive numbers, and 0 itself is not a positive number. Positive numbers and negative numbers represent quantities with opposite meanings. Positive numbers are usually preceded by a "+"symbol, which can usually be omitted. Negative numbers are marked with minus sign "-"and positive numbers, such as? 2 stands for the antonym of 2. On the number axis, positive numbers are all on the right side of 0, and the earliest record of positive numbers is China's ancient mathematical work "Nine Chapters Arithmetic".