Question

1. $6k + 21$

$3(2k + 7)$
$\text{gcf: } 3$

1. $8r + 15$

$\text{gcf: }$
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multiple-choice question
why is number 11 prime?
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\square\text{ because their gcf is 1}
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\square\text{ because both terms do not have a variable}
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\text{rewatch}

Explanation:

Step1: List factors of 8

Factors of $8$: $1, 2, 4, 8$

Step2: List factors of 15

Factors of $15$: $1, 3, 5, 15$

Step3: Identify common factors

Common factor: $1$

Step4: Factor the expression (if possible)

Since GCF is 1, $8r+15$ cannot be factored further.

A prime number has exactly two distinct positive divisors: 1 and itself. The GCF of 11 with any number not a multiple of 11 is 1, but more directly, 11's only divisors are 1 and 11, which aligns with the first option's logic (its GCF with 1 is 1, and it has no other factors).

Answer:

GCF: $1$
The expression $8r+15$ remains in its original form as it cannot be factored.

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For the multiple-choice question: