Beginning with the graph of f(x) = x2, what transformations are needed to form g(x) = 3(x + 2)2 – 1?

The graph of g(x) is narrower than f(x) and is shifted to the right 2 units and down 1 unit.
The graph of g(x) is narrower than f(x) and is shifted to the left 2 units and down 1 unit.
The graph of g(x) is wider than f(x) and is shifted to the left 2 units and down 1 unit.
The graph of g(x) is wider than f(x) and is shifted to the right 2 units and down 1 unit.

1 answer

Let's analyze the transformation needed to go from \( f(x) = x^2 \) to \( g(x) = 3(x + 2)^2 - 1 \).

  1. Identifying Transformations:

    • The term \( (x + 2) \) indicates a horizontal shift. Since it’s \( x + 2 \), the graph shifts to the left by 2 units.
    • The coefficient \( 3 \) in front of \( (x + 2)^2 \) stretches the graph vertically. Because it is greater than 1, the graph of \( g(x) \) is narrower than \( f(x) \).
    • The term \( -1 \) at the end indicates a vertical shift down by 1 unit.
  2. Combining Transformations:

    • Start with \( f(x) = x^2 \).
    • Shift left 2 units, yielding \( f(x + 2) = (x + 2)^2 \).
    • Then, apply the vertical stretch by 3: \( g(x) = 3(x + 2)^2 \).
    • Finally, shift down 1 unit: \( g(x) = 3(x + 2)^2 - 1 \).
  3. Conclusion:

    • So the transformations needed to form \( g(x) \) from \( f(x) \) are:
      • Shift to the left 2 units.
      • Vertical stretch: narrower than \( f(x) \).
      • Shift down 1 unit.

Therefore, the correct description of the transformation needed is: The graph of g(x) is narrower than f(x) and is shifted to the left 2 units and down 1 unit.