-3*-2*-2=6*-2=-12 because negative multiplied by negative is positive
23 is one of the answers, and -23, because negative times negative is positive.
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Answer:
Consider f: N → N defined by f(0)=0 and f(n)=n-1 for all n>0.
Step-by-step explanation:
First we will prove that f is surjective. Let y∈N be any natural number. Define x as the number x=y+1. Then x∈N, and f(x)=x-1=(y+1)-1=y. We conclude that f is surjective.
However, f is not injective. Take x1=0 and x2=1. Then x1≠x2 but f(x1)=0 and f(x2)=x2-1=1-1=0. We have shown that there are two natural numbers x1,x2 such that x1≠x2 but f(x1)=f(x2), that is, f is not injective.
Note:
If 0∉N in your definition of natural numbers, the same reasoning works with the function f: N → N defined by f(1)=1 and f(n)=n-1 for all n>1. The only difference is that you consider x1=1, x2=2 for the injectivity.
Given:
3 kids
72 is the product of their ages.
There is a youngest child.
This means that all three are of different ages. We need to factor 72 into 3 integers.
Let us use prime factorization:
72 ÷ 2 = 36
36 ÷ 2 = 18
18 ÷ 2 = 9
9 ÷ 3 = 3
Prime factors are: 2 x 2 x 2 x 3 x 3 OR 2³ x 3²
3 ages.
eldest = 3³ = 9
middle = 2² = 4
youngest = 2¹ = 2
2 x 4 = 8
8 x 9 = 72
