5.( 1)-9.7 1 1 (2)0.755 (3)235.000 (4)324.000

6. Rational numbers refer to all fractions and integers, which can be converted into finite decimals or infinite circulating decimals.

Irrational number refers to the number in real number that cannot be accurately expressed as the ratio of two integers, that is, infinite acyclic decimal.

Square root: rational number: 0 1 4 9 irrational number: 2 3 5 6 7 8 10.

Cube root: rational number: 0 1 8 irrational number: 2 3 4 5 6 7 9 10.

7.( 1)& lt； (2)& lt； (3)& lt；

8.( 1)√2(√2+2)=√2*√2+2*√2=2+2√2

(2) √ 3 (√ 3+1√ 3) = √ 3 * √ 3+1√ 3 = 3+1= 4 Note: √ stands for the root sign.