the additive inverse of a number a is the number that, when added to 'a', yields zero. This number is also known as the opposite (number), sign change, and negation.
So the Additive inverse of -2 is 2. ∴ -2+2=0
b) Additive identity of −5
Additive identity is the value when added to a number, results in the original number. When we add 0 to any real number, we get the same real number.
-5 + 0 = -5. Therefore, 0 is the additive identity of any real number.
c) additive inverse of 3
Two numbers are additive inverses if they add to give a sum of zero. 3 and -3 are additive inverses since 3 + (-3) = 0. -3 is the additive inverse of 3.
d). multiplicative identity of 19
an identity element (such as 1 in the group of rational numbers without 0) that in a given mathematical system leaves unchanged any element by which it is multiplied
Multiplicative identity if 19 is 1 only, since 19 x 1 = 19.
e) multiplicative inverse of 7
Dividing by a number is equivalent to multiplying by the reciprocal of the number. Thus, 7 ÷7=7 × 1⁄7 =1. Here, 1⁄7 is called the multiplicative inverse of 7.
So 7 x = x2 -18 so you get the quadratic x^2 -7x -18 and then get 2 x -9= -18 and 2 + -9 = -7 so you get (x + 2) ( x - 9) so the positive solution would be x-9 = 0 so x= 9. Hope this helps :)
