1. The absolute value of a number is the distance from zero, so both 6, or -6 are have the same absolute value, |6|=|-6|, and |x| >=0 whatever the number of Xis, positive or negative.

2. the square root and cube root,

latex \times{(-2)}$=4,  and 2=4.

the cube root , the x could be positive or negative, because the -2 =-8

and 2 =8.

3. the rational number and irrational number,

rational, include :whole number, fraction, natural, the decimal which can  turn to be fraction that repeating and terminating.

The decimal form of an irrational number is a non-repeating and non-terminating decimal number