Math Problem Statement

Write each quadratic equation in the form y = a(x - h)^2 + k. Then find its vertex. y = -2x^2 + 3x - 1

Solution

The given quadratic equation is:

y=2x2+3x1y = -2x^2 + 3x - 1

We are asked to rewrite this equation in vertex form, which is:

y=a(xh)2+ky = a(x - h)^2 + k

where (h,k)(h, k) is the vertex of the parabola.

Step 1: Completing the Square

First, we'll complete the square to rewrite the quadratic in vertex form.

  1. Factor out the coefficient of x2x^2 from the first two terms:

y=2(x232x)1y = -2(x^2 - \frac{3}{2}x) - 1

  1. Complete the square:
    • Take half of the coefficient of xx inside the parentheses, 32\frac{-3}{2}, which is 34\frac{-3}{4}.
    • Square this value: (34)2=916\left(\frac{3}{4}\right)^2 = \frac{9}{16}.

Now add and subtract this inside the parentheses to complete the square:

y=2(x232x+916916)1y = -2\left(x^2 - \frac{3}{2}x + \frac{9}{16} - \frac{9}{16}\right) - 1

  1. Simplify:
    • Combine the perfect square and adjust the constant outside:

y=2[(x34)2916]1y = -2\left[\left(x - \frac{3}{4}\right)^2 - \frac{9}{16}\right] - 1

  1. Distribute:
    • Distribute the 2-2 to both terms inside the brackets:

y=2(x34)2+18161y = -2\left(x - \frac{3}{4}\right)^2 + \frac{18}{16} - 1

  1. Simplify constants:
    • Simplify the constant terms:

y=2(x34)2+18161616y = -2\left(x - \frac{3}{4}\right)^2 + \frac{18}{16} - \frac{16}{16}

y=2(x34)2+216y = -2\left(x - \frac{3}{4}\right)^2 + \frac{2}{16}

y=2(x34)2+18y = -2\left(x - \frac{3}{4}\right)^2 + \frac{1}{8}

Step 2: Identify the vertex

Now that we have the equation in vertex form:

y=2(x34)2+18y = -2\left(x - \frac{3}{4}\right)^2 + \frac{1}{8}

The vertex (h,k)(h, k) is (34,18)\left(\frac{3}{4}, \frac{1}{8}\right).

Final Answer:

  • Vertex form: y=2(x34)2+18y = -2\left(x - \frac{3}{4}\right)^2 + \frac{1}{8}
  • Vertex: (34,18)\left(\frac{3}{4}, \frac{1}{8}\right)

Would you like further explanation or details on any of the steps?

Here are some related questions you might consider:

  1. What is the axis of symmetry for this quadratic equation?
  2. How does the value of a=2a = -2 affect the shape of the parabola?
  3. How do you determine the direction in which the parabola opens?
  4. Can you find the y-intercept of the original quadratic equation?
  5. How do you find the x-intercepts of the quadratic equation?

Tip: Completing the square is a helpful technique not only for finding the vertex form of a quadratic equation but also for solving quadratic equations algebraically.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Vertex Form
Completing the Square

Formulas

Vertex form of a quadratic: y = a(x - h)^2 + k
Quadratic equation standard form: y = ax^2 + bx + c
Formula for completing the square: (x + b/2)^2

Theorems

The Vertex Formula

Suitable Grade Level

Grades 9-11