Question

Rewrite 9x + 81 using a common factor.

A: 9x(x + 81)
B: 9x(x + 9)
C: 9(x + 81)
D: 9(x + 9)

Answer 1

Option D; 9(x + 9)

Explanation:

1. 9x + 81 (I am finding the answer by testing each option to see if it corresponds to the question)
2. A: 9x(x + 81)
3. 
   `9x^(2)` + 729x
4. (This is clearly not the correct answer since no parts of this solution corresponds as the right factoring to the question)
5. B: 9x(x + 9)
6. 
   `9x^(2)`
   `9x^(2)` + 81
7. (This is not right answer either since the first term has to 9x not
   `9x^(2)`)
8. C: 9(x + 81)
9. 9x + 729
10. (Although the first term is corresponding, the second term isn't, therefore, this is not the right answer)
11. D: (This is the right answer automatically since by process of elimination, this is the last option and the rest were incorrect, therefore, this has to be the right answer)
12. 9(x + 9)
13. 9x + 81

Answer: D; 9(x + 9)

Hope this helped! :D

Answer 2

D: 9(x + 9)

Explanation:

If you divide the equation 9x+81 by 9

you get x+9, making 9 your common factor.

9(x+9)