# SAT Math Multiple Choice Question 129: Answer and Explanation

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**Question: 129**

**9.** What is the value of (2x^{2} + 4x + 8) - (2x^{2} - 4x + 7) ?

- A. 4x
^{2}+ 8x + 15 - B. 2x
^{2}+ x + 1 - C. 8x + 1
- D. 8x + 15

**Correct Answer:** C

**Explanation:**

C To solve this question, rearrange the expressions (2x^{2} + 4x + 8) and (2x^{2} - 4x + 7) in order to place the similar terms next to each other. Doing so will give you 2x^{2} - 2x^{2} + 4x - (-4x) + 8 - 7 (remember to distribute the negative sign for each of the terms in the second expression). Simplifying this new expression will yield 0 + 8x + 1, or 8x + 1, (C). Another way to approach this question would be to plug in a simple number for x, such as x = 2, and match your target value with the values in the answer choices.