Given the table of values, complete the table for the quadratic equation y=−6x2+3x+8 to find the values of the high or low point of the parabola.

x y
−1 −1
−0.75 2.375
−0.5 5
−0.25
0 8
0.25 8.375
0.5
0.75
1 5
Which of the following is correct?

(1 point)
Responses

(0.25,8.375) is the low point on the parabola.
left parenthesis 0.25 comma 8.375 right parenthesis is the low point on the parabola.

(0.5,9) is the high point on the parabola.
left parenthesis 0.5 comma 9 right parenthesis is the high point on the parabola.

(0.25,8.375) is the high point on the parabola.
left parenthesis 0.25 comma 8.375 right parenthesis is the high point on the parabola.

(−1,−1) is the low point on the parabola.

1 answer

To find the high or low point (the vertex) of the quadratic equation \(y = -6x^2 + 3x + 8\), we can use the formula for the x-coordinate of the vertex, which is given by:

\[ x = -\frac{b}{2a} \]

In this case, \(a = -6\) and \(b = 3\).

Calculating the x-coordinate of the vertex:

\[ x = -\frac{3}{2(-6)} = -\frac{3}{-12} = \frac{1}{4} = 0.25 \]

Now we substitute \(x = 0.25\) back into the equation to find the corresponding y-coordinate:

\[ y = -6(0.25)^2 + 3(0.25) + 8 \] \[ y = -6(0.0625) + 0.75 + 8 \] \[ y = -0.375 + 0.75 + 8 \] \[ y = 0.375 + 8 = 8.375 \]

The vertex of the parabola is \((0.25, 8.375)\). Because the quadratic opens downwards (since \(a < 0\)), this point is a high point (maximum) of the parabola.

Now, looking at the options given:

  1. (0.25, 8.375) is the low point on the parabola. (Incorrect)
  2. (0.5, 9) is the high point on the parabola. (Incorrect)
  3. (0.25, 8.375) is the high point on the parabola. (Correct)
  4. (−1, −1) is the low point on the parabola. (Incorrect)

The correct response is:

(0.25, 8.375) is the high point on the parabola.