Kaylee123
Answered

Cynthia made the conjecture that the sum of any prime number and any composite number is a composite number.


Which equation is a counterexample to her conjecture?


A.

11 + 2 = 13


B.

5 + 8 = 13


C.

13 + 2 = 15


D.

11 + 9 = 20

Verified Answer :

SchwarzschildRadius

Well,

We will need an equation in the form of:
(prime no.) + (composite no.) = (prime no.)

Options C and D immediately are rejected because the result is a composite number.

Option A looks like it could be a counterexample, but 2 is a prime number.

That leaves option B, which is the correct option.

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