Question

leveled practice in 1–4, factor the expression. 1. 21a + 9. the gcf of 21 and 9 is 3. 3 × \boxed{} = 21a 3 × \boxed{} = 9 the factored expression is \boxed{}

Explanation:

Step1: Find the first missing term

We know that \(3\times\) (missing term) \( = 21a\). To find the missing term, we divide \(21a\) by \(3\). So, \(\frac{21a}{3}=7a\).

Step2: Find the second missing term

We know that \(3\times\) (missing term) \( = 9\). To find the missing term, we divide \(9\) by \(3\). So, \(\frac{9}{3}=3\).

Step3: Write the factored expression

Using the distributive property \(ab + ac=a(b + c)\), where \(a = 3\), \(b = 7a\), and \(c = 3\), the factored expression is \(3(7a + 3)\).

Answer:

First box: \(7a\)
Second box: \(3\)
Factored expression: \(3(7a + 3)\)