Graph and compare the shapes and key features of the functions f(x)=(x+2)^2 and g(x)=2x+4. Which of the following statements is true?

Responses

f(x) is a straight line and g(x) is a u-shaped curve

both functions have a minimum value of (-2, 0)

f(x) is a u-shaped curve and g(x) is a straight line

both functions have a x-intercept of (4, 0)

1 answer

To analyze and compare the functions \( f(x) = (x + 2)^2 \) and \( g(x) = 2x + 4 \), we can look at their shapes and key features.

Function Analysis

  1. For \( f(x) = (x + 2)^2 \):

    • Shape: This is a quadratic function, which means it is a parabola.
    • Direction: The parabola opens upwards because the coefficient of the squared term is positive.
    • Vertex: The vertex of the parabola is at the point \((-2, 0)\), which gives the minimum value of the function.
    • x-intercept: Set \( f(x) = 0 \) to find the x-intercept: \[ (x + 2)^2 = 0 \implies x + 2 = 0 \implies x = -2 \quad \text{(Point: } (-2, 0) \text{)} \]
  2. For \( g(x) = 2x + 4 \):

    • Shape: This is a linear function, which means it is a straight line.
    • Slope: The slope is 2, indicating the line rises steeply as \( x \) increases.
    • y-intercept: To find where it crosses the y-axis, when \( x = 0 \): \[ g(0) = 2(0) + 4 = 4 \quad \text{(Point: } (0, 4) \text{)} \]
    • x-intercept: Set \( g(x) = 0 \) to find the x-intercept: \[ 2x + 4 = 0 \implies 2x = -4 \implies x = -2 \quad \text{(Point: } (-2, 0) \text{)} \]

Summary of Key Features

  • \( f(x) \) is a u-shaped curve (parabola) with a minimum at \((-2, 0)\) and x-intercept at \((-2, 0)\).
  • \( g(x) \) is a straight line with an x-intercept at \((-2, 0)\) and a y-intercept at \((0, 4)\).

Evaluating the Statements

  1. f(x) is a straight line and g(x) is a u-shaped curve: False (f(x) is a parabola, g(x) is a line).
  2. Both functions have a minimum value of (-2, 0): False (only f(x) has a minimum at this point; g(x) goes to infinity).
  3. f(x) is a u-shaped curve and g(x) is a straight line: True (f(x) is a parabola, g(x) is a line).
  4. Both functions have an x-intercept of (4, 0): False (Both have x-intercept at (-2, 0)).

Conclusion

The true statement is: f(x) is a u-shaped curve and g(x) is a straight line.