Answer:
-2 < a
Step-by-step explanation:
Y = 1 + i
<span>(1 + i)^3 - 3 * (1 + i)^2 + k - 1 = -i </span>
<span>(1 + 3i + 3i^2 + i^3) - 3 * (1 + 2i + i^2) + k - 1 = -i </span>
<span>1 + 3i - 3 - i - 3 - 6i + 3 + k - 1 = -i </span>
<span>1 - 3 - 3 + 3 - 1 + 3i - i - 6i + k = -i </span>
<span>-3 - 4i + k = -i </span>
<span>k = 4i - i + 3 </span>
<span>k = 3i + 3 </span>
<span>k = 3 * (1 + i) </span>
<span>k = 3y</span>
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.
If there's 21 spoons and 27 forks than there are 48 utensils, and the ratio of spoon to total stilis is 21/48, and if you reduce that it is 7/16. So your answer is B. 7/16.<span />
