SAT Math Multiple Choice Practice Question 557: Answer and Explanation

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Question: 557

14. Which of the following is equal to 3x + 9y +12 ?

A. 3(x + 3y + 9)
B. 3(x + 3y) + 12
C. 3(x + 3y) + 4
D. 3(x + 6y + 9)
E. 3x(3y + 4)

Correct Answer: B

Explanation:

B Although all three parts of 3x + 9y + 12 are divisible by 3, the expression 3(x + 3y + 4) is not among the answers, so your best bet is to try each of the answers. A is out, because if 3 is factored out of the expression, The last number should be a 4, not a 9. Putting brackets around only part of the expression, such as (3x + 9y), does not change the value of the entire expression. Since (3x + 9y) +12 = 3(x + 3y) + 12, B is correct. You're done! There is no need to try out any further answer choices.

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