yes
Yes.
It is the number with the same magnitude (absolute value) and the opposite sign.
You take its reciprocal, that is you divide 1 by the number. A rational number can be written as a fraction with integer values in both the numerator and denominator, j/k. The multiplicative inverse of a number is what you have to multiply by to get a product of 1. Putting these ideas together, the multiplicative inverse is the reciprocal, or k/j: (j/k) * (k/j) = 1.
All rational numbers, with the exception of zero (0), have a multiplicative inverse. In fact, all real numbers (again, except for zero) have multiplicative inverses, though the inverses of irrational numbers are themselves irrational. Even imaginary numbers have multiplicative inverses (the multiplicative inverse of 5i is -0.2i - as you can see the inverse itself is also imaginary). Even complex numbers (the sum of an imaginary number and a real number) have multiplicative inverses (the inverse of [5i + 2] is [-5i/29 + 2/29] - similar to irrational and imaginary numbers, the inverse of a complex number is itself complex). The onlynumber, in any set of numbers, that does not have a multiplicative inverse is zero.
If the multiplicative inverse exists then, by definition, the product is 1 which is rational.
The additive inverse of EVERY positive rational number is a negative number.
No. The additive inverse of zero or a negative rational number is not negative.
of course
No, it is not. 3/5 is rational and its multiplicative inverse is 5/3 which is not an integer.
All but 0.
yes
Zero.
Zero.
Yes. Both the additive inverse and the multiplicative inverse would be irrational in this case. For example, if a and b are integers, a/b is rational by definition; in this case, b/a would also be rational, being the ratio of two integers.
Yes.
The number is 7.