1.which values for a and b make the statement (a + 2)(b - 9) = 0 true? a. a = 2, b = -9b. a = -2, b = 9c. a = -2, b = -9d. a = 2, y = 92.which values for x and y make the statement (x - 9)(y + 4) = 0 true? a. x = -9, y = 4b. x = 9, y = 4c. x = -9, y = -4d. x = 9, y = -43.which of the following gives an example of a set that is closed under addition? a. the sum of an even number and an even numberb. the sum of an odd number and an odd numberc. the sum of a prime number and a prime numberd. none of these are an example of the closure property.4.which of the following gives an example of a set that is closed under multiplication? choose all that apply. a. the product of a prime number and a prime numberb. the product of a whole number and a whole numberc. the product of a negative number and a negative numberd. the product of a natural number and a natural number

Answer :

1. (a + 2)(b - 9) = 0

If the product of two numbers is given to be 0, then either of the number is equal to 0

⇒ a + 2 = 0 , b - 9 = 0

⇒ a = -2 , b = 9

Therefore, The correct option is b. a = -2, b = 9

2. (x - 9)(y + 4) = 0

If the product of two numbers is given to be 0, then either of the number is equal to 0

⇒ (x - 9) = 0 , (y + 4) = 0

⇒ x = 9 , y = -4

Therefore, The correct option is d. x = 9, y = -4

3.  

The sum of an even number and an even number

Since, The sum of an even number and an even number is always even number. So, TRUE

The sum of an odd number and an odd number

Since, The sum of an odd  umber and an odd number is not and= odd number. So, FALSE

The sum of a prime number and a prime number

FALSE. Counter Example : 3 + 5 = 8 , 8 is not a prime.

None of these are an example of the closure property

First part is an example of closure property. So, FALSE

Therefore, The correct option is a.

4.

The product of a prime number and a prime number

FALSE, Counter Example : 3 × 5 = 15 , 15 is not a prime.

The product of a whole number and a whole number

TRUE

The product of a negative number and a negative number

FALSE, Counter Example : - 3 × - 5 = 15 , 15 is not a negative number.

The product of a natural number and a natural number

TRUE

Therefore, The correct options are : b. and d.