Math Problem Statement

If y = -2x^2 + 160x, then the maximum value of y is: a. 40 b. 6400 c. 80 d. 3200

Solution

The given equation is:

y=2x2+160xy = -2x^2 + 160x

This is a quadratic equation in the form y=ax2+bx+cy = ax^2 + bx + c, where a=2a = -2, b=160b = 160, and c=0c = 0. Since a<0a < 0, the parabola opens downwards, and the vertex represents the maximum value of yy.

Step 1: Find the xx-coordinate of the vertex

The formula for the xx-coordinate of the vertex for a quadratic equation is:

x=b2ax = -\frac{b}{2a}

Substitute a=2a = -2 and b=160b = 160:

x=1602(2)=1604=40x = -\frac{160}{2(-2)} = \frac{160}{4} = 40

So, the xx-coordinate of the vertex is x=40x = 40.

Step 2: Find the maximum value of yy

Substitute x=40x = 40 into the equation y=2x2+160xy = -2x^2 + 160x:

y=2(40)2+160(40)y = -2(40)^2 + 160(40)

Calculate step by step:

  1. 402=160040^2 = 1600,
  2. 2(1600)=3200-2(1600) = -3200,
  3. 160(40)=6400160(40) = 6400,
  4. 3200+6400=3200-3200 + 6400 = 3200.

Thus, the maximum value of yy is:

3200\boxed{3200}

Correct answer:

d. 3200

Would you like further clarification or more examples?

Here are 5 related questions to explore further:

  1. What is the general formula for the vertex of a quadratic function?
  2. How can we determine if a parabola opens upwards or downwards?
  3. Can you calculate the minimum value of a quadratic function when a>0a > 0?
  4. How do you rewrite a quadratic equation in vertex form?
  5. How would the solution change if the coefficient of x2x^2 were positive?

Tip: Always double-check the sign of aa in a quadratic equation to determine whether the vertex gives a maximum or minimum.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Maximum and Minimum Values of Quadratic Equations

Formulas

Vertex formula: x = -b / 2a
Quadratic equation: y = ax^2 + bx + c

Theorems

Vertex theorem for quadratic functions

Suitable Grade Level

Grades 9-11