What can you say about the parity of a number and its square?
The parity of a number and its square is always the same.
Step 1: Consider an even number n = 2k
Step 2: n² = (2k)² = 4k², which is even
Step 3: Consider an odd number m = 2k + 1
Step 4: m² = (2k+1)² = 4k² + 4k + 1 = 2(2k² + 2k) + 1, which is odd
∴ If a number is even, its square is even. If a number is odd, its square is odd.
Explanation
The chapter discusses properties of squares including parity. When we multiply two even numbers, the result is even. When we multiply two odd numbers, the result is odd. Since a square is a number multiplied by itself, the parity is preserved.
Solution Steps
Step 1: Consider an even number n = 2k
Step 2: n² = (2k)² = 4k², which is even
Step 3: Consider an odd number m = 2k + 1
Step 4: m² = (2k+1)² = 4k² + 4k + 1 = 2(2k² + 2k) + 1, which is odd