Question 305770: If a and b are odd integers, which of the following must also be an odd integer?
I. (a + 1)b
II. II. (a + 1) + b
III. III. (a + 1) – b
a) I only b) II only c) III only d) I & II e) II & III
Answer by toidayma(44)   (Show Source):
You can put this solution on YOUR website! You should know the basic formulas of odd and even number:
odd + odd = even,
odd - odd = even,
odd + even = odd,
odd - even = odd,
even + even = even,
even - even = even,
odd*odd = odd,
odd *even = even and
even * even = even.
I. With(a+1)*b, since a is odd, a + 1 is even, and since b is odd, we have (a+1)*b = even.
II. With (a+1) + b, since a is odd, a + 1 is even, and since b is odd, we have (a+1) + b is odd.
III. With (a+1) - b, since a is odd, a + 1 is even, and since b is odd, we have (a+1) - b is odd.
Therefore, II and III are odd, thus the answer is e>II & III
|
|
|
