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identify the vertex, axis of symmetry, and min/max value of each. 18) $…

Question

identify the vertex, axis of symmetry, and min/max value of each.

  1. $f(x) = 2x^2 - 3$
  2. $f(x) = -x^2 - 10x$
  3. $f(x) = 3x^2 + 24x + 42$
  4. $f(x) = -(x - 3)^2$
  5. $f(x) = (x - 2)^2 + 1$

Explanation:

Step1: Analyze \( f(x) = 2x^2 - 3 \)

The vertex form of a parabola is \( f(x)=a(x - h)^2 + k \), where \((h,k)\) is the vertex. For \( f(x)=2x^2 - 3 \), we can rewrite it as \( f(x)=2(x - 0)^2 - 3 \). So \( h = 0 \), \( k=-3 \), vertex is \((0, -3)\). The axis of symmetry is \( x = h = 0 \). Since \( a = 2>0 \), the parabola opens up, so it has a minimum value at \( k=-3 \).

Step2: Analyze \( f(x)=-x^2 - 10x \)

Complete the square: \( f(x)=-(x^2 + 10x)=-(x^2 + 10x + 25 - 25)=-(x + 5)^2 + 25 \). So vertex is \((-5, 25)\), axis of symmetry \( x=-5 \). Since \( a=-1<0 \), it opens down, maximum value is \( 25 \).

Step3: Analyze \( f(x)=3x^2 + 24x + 42 \)

Factor out 3: \( f(x)=3(x^2 + 8x)+42 \). Complete the square inside the parentheses: \( x^2 + 8x=(x + 4)^2 - 16 \). So \( f(x)=3((x + 4)^2 - 16)+42=3(x + 4)^2 - 48 + 42=3(x + 4)^2 - 6 \). Vertex \((-4, -6)\), axis of symmetry \( x=-4 \). \( a = 3>0 \), minimum value \(-6\).

Step4: Analyze \( f(x)=-(x - 3)^2 - \dots \) (assuming the missing part doesn't affect form analysis). Vertex form is \( f(x)=a(x - h)^2 + k \), so vertex \((3, k)\) (depending on the missing term), axis of symmetry \( x = 3 \). Since \( a=-1<0 \), it opens down, maximum at \( k \).

Step5: Analyze \( f(x)=(x - 2)^2 + 1 \)

In vertex form \( f(x)=1(x - 2)^2 + 1 \), so vertex \((2, 1)\), axis of symmetry \( x = 2 \). \( a = 1>0 \), minimum value \( 1 \).

Answer:

  1. Vertex: \((0, -3)\), Axis of Symmetry: \( x = 0 \), Minimum Value: \(-3\)
  2. Vertex: \((-5, 25)\), Axis of Symmetry: \( x=-5 \), Maximum Value: \( 25 \)
  3. Vertex: \((-4, -6)\), Axis of Symmetry: \( x=-4 \), Minimum Value: \(-6\)
  4. (Assuming form \( f(x)=-(x - 3)^2 + k \)) Vertex: \((3, k)\), Axis of Symmetry: \( x = 3 \), Maximum Value: \( k \) (depends on missing term)
  5. Vertex: \((2, 1)\), Axis of Symmetry: \( x = 2 \), Minimum Value: \( 1 \)