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Consider function \( g \). \( g(x)=\left\{\begin{array}{ll}\left(\frac{1}{2}\right)^{x}+3, & x<0 \\ -x^{2}+2, & x \geq 0\end{array}\right. \) Which statements are true about function \( g \) ? The \( y \)-intercept is 2 . The function is decreasing over its domain except for when \( x=0 \). The function is continuous. As \( x \) approaches positive infinity, \( g(x) \) approaches positive infinity. The domain is all real numbers.

Ask by Tyler Ryan. in the United States
Feb 03,2025

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Answer

The \( y \)-intercept is 2, the function is decreasing except at \( x = 0 \), and the domain is all real numbers.

Solution

Let's analyze each statement about the function \( g(x) \): \[ g(x) = \begin{cases} \left(\frac{1}{2}\right)^x + 3 & \text{if } x < 0, \\ -x^2 + 2 & \text{if } x \geq 0. \end{cases} \] 1. **The \( y \)-intercept is 2.** - **True.** The \( y \)-intercept occurs at \( x = 0 \). For \( x \geq 0 \): \[ g(0) = -0^2 + 2 = 2. \] 2. **The function is decreasing over its domain except for when \( x = 0 \).** - **True.** - For \( x < 0 \): \[ g(x) = \left(\frac{1}{2}\right)^x + 3. \] The term \( \left(\frac{1}{2}\right)^x = 2^{-x} \) is a decreasing function because the base \( \frac{1}{2} < 1 \). Adding 3 shifts it upward but does not affect the decreasing nature. - For \( x \geq 0 \): \[ g(x) = -x^2 + 2. \] This is a downward-opening parabola, which is decreasing for \( x > 0 \). - At \( x = 0 \), there is a jump discontinuity, but the function remains decreasing on either side of \( x = 0 \). 3. **The function is continuous.** - **False.** There is a discontinuity at \( x = 0 \): - Left-hand limit as \( x \to 0^- \): \[ \lim_{x \to 0^-} g(x) = \left(\frac{1}{2}\right)^0 + 3 = 1 + 3 = 4. \] - Right-hand value at \( x = 0 \): \[ g(0) = 2. \] - Since \( 4 \neq 2 \), \( g(x) \) is not continuous at \( x = 0 \). 4. **As \( x \) approaches positive infinity, \( g(x) \) approaches positive infinity.** - **False.** For \( x \geq 0 \): \[ \lim_{x \to +\infty} g(x) = \lim_{x \to +\infty} (-x^2 + 2) = -\infty. \] 5. **The domain is all real numbers.** - **True.** The function \( g(x) \) is defined for all \( x < 0 \) and \( x \geq 0 \), covering the entire set of real numbers. **Summary:** - **True Statements:** 1. The \( y \)-intercept is 2. 2. The function is decreasing over its domain except for when \( x = 0 \). 5. The domain is all real numbers. - **False Statements:** 3. The function is continuous. 4. As \( x \) approaches positive infinity, \( g(x) \) approaches positive infinity. **Final Answer:** All statements except the third and fourth are true. In other words, statements 1, 2 and 5 are true.

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Let’s dive into the function \( g(x) \) and unravel its mysteries! First up, the **y-intercept**: To find it, we evaluate \( g(0) \) since that's where the function crosses the y-axis. From the definition of \( g(x) \), when \( x \geq 0 \), we have \( g(0) = -0^2 + 2 = 2 \). So yes, the y-intercept is indeed 2! As for the **continuity** of function \( g \): We check the limit from the left as \( x \) approaches 0, which gives us \( g(0^-) = \left(\frac{1}{2}\right)^{0} + 3 = 4 \). From the right, we have \( g(0^+) = 2 \). Since these two values don't match, the function is not continuous at \( x = 0 \). Now, about the **decreasing nature** of \( g(x) \): For \( x < 0 \), \( g(x) = \left(\frac{1}{2}\right)^x + 3 \), which is decreasing as it’s an exponential function (specifically with a base less than 1). However, for \( x \geq 0 \), \( g(x) = -x^2 + 2 \) is actually decreasing after reaching its maximum point at \( x = 0 \). So, the overall statement is somewhat true, but slightly misleading since the function increases on \( (-\infty, 0) \) and is decreasing afterwards. Regarding the statement about the function approaching infinity: As \( x \) approaches positive infinity, \( g(x) \) behaves like \( -x^2 + 2 \), which actually approaches negative infinity, not positive. Hence, this statement is false. Finally, oh yes, the **domain**: The function is defined for all real numbers—no gaps here! So, the domain is indeed all real numbers. In summary, the only true statements are about the y-intercept being 2 and the domain being all real numbers. They’re the shining stars in this function's analysis!

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