Answer:
Lets say that P(n) is true if n is a prime or a product of prime numbers. We want to show that P(n) is true for all n > 1.
The base case is n=2. P(2) is true because 2 is prime.
Now lets use the inductive hypothesis. Lets take a number n > 2, and we will assume that P(k) is true for any integer k such that 1 < k < n. We want to show that P(n) is true. We may assume that n is not prime, otherwise, P(n) would be trivially true. Since n is not prime, there exist positive integers a,b greater than 1 such that a*b = n. Note that 1 < a < n and 1 < b < n, thus P(a) and P(b) are true. Therefore there exists primes p1, ...., pj and pj+1, ..., pl such that
p1*p2*...*pj = a
pj+1*pj+2*...*pl = b
As a result
n = a*b = (p1*......*pj)*(pj+1*....*pl) = p1*....*pj*....pl
Since we could write n as a product of primes, then P(n) is also true. For strong induction, we conclude than P(n) is true for all integers greater than 1.
Answer:
7^2
Step-by-step explanation:
7*7=49
4^3=43
49>43
<span>A. Calculate the value of x.</span>
Answer: the speed of the current is 0.6 mph
Step-by-step explanation:
Let x represent the speed of the current.
James is kayaking. He can row 3 mph in still water. If he can travel 6 miles downstream. Assuming he went with the current, it means that his total speed while travelling downstream is (3 + x)
Time = distance/speed
Time taken to travel downstream is
6/(3 + x)
In the same amount of time, he can travel 4 miles upstream. Assuming he went against the current, it means that his total speed while travelling downstream is (3 - x). Time taken to travel upstream is
4/(3 - x)
Since the time is the same, then
6/(3 + x) = 4/(3 - x)
Cross multiplying, it becomes
6(3 - x) = 4(3 + x)
18 - 6x = 12 + 4x
4x + 6x = 18 - 12
10x = 6
x = 6/10
x = 0.6 mph