ACT PREP The radius of a circle is \( x^{3}+7 x \) What is the diameter? \( 2 x^{3}+14 x \) \( 2 x^{3}+7 x \) \( 2 x^{3}+7 x+14 \) \( x^{3}+14 x \) \( x^{3}+7 x+21 \)

To find the diameter of a circle, you simply double the radius. Given that the radius is \( x^{3}+7x \), the diameter would be \( 2 \times (x^{3}+7x) = 2x^{3}+14x \). So the correct answer is \( 2x^{3}+14x \)! Remember, knowing how to manipulate equations like this is crucial for the ACT, which tests not just mathematical skills but also your ability to apply concepts quickly. Practice makes perfect! Additionally, be sure to double-check your algebra with a quick review of multiplication rules. It's easy to slip up, especially when variables are involved! Look out for simple mistakes, like forgetting to distribute correctly or misplacing terms. Every point counts on the ACT!