Find Negative Area of y-4=-(x-4)²: Quadratic Function Analysis

Question

Find the negative area of the function

y4=(x4)2 y-4=-(x-4)^2

Video Solution

Solution Steps

00:00 Find the negative domain of the function
00:03 Use the shortened multiplication formulas and expand the parentheses
00:14 Arrange the equation so that it remains a function
00:19 Notice that the coefficient of X squared is negative
00:23 When the coefficient is negative, the function is concave down
00:30 Now we want to find the intersection points with the x-axis
00:34 At the intersection points with the x-axis, Y=0, substitute and solve
00:39 Change from negative to positive
00:44 Extract the root
00:50 When extracting a root there are always 2 solutions (positive and negative)
00:54 Solve each possibility to find the points, isolate X
01:09 These are the intersection points with the x-axis
01:14 Graph the function according to the intersection points and type of function
01:20 The function is negative while it's below the x-axis
01:30 And this is the solution to the problem

Step-by-Step Solution

The given equation is y4=(x4)2 y - 4 = -(x - 4)^2 .

First, identify the vertex: the equation is in vertex form y=(x4)2+4 y = -(x - 4)^2+4 with vertex at (4,4)(4, 4). The parabola opens downwards because the coefficient of (x4)2(x-4)^2 is negative.

Next, find the x-intercepts by setting y=0 y = 0 :

0=(x4)2+4 0 = -(x - 4)^2 + 4

(x4)2=4 (x - 4)^2 = 4

Taking the square root of both sides gives x4=±2 x - 4 = \pm 2 .

So, the solutions are x=6 x = 6 and x=2 x = 2 .

The parabola is negative between these x-intercepts. Since it opens downwards, the function is negative outside the interval [2,6][2, 6], i.e., for x<2 x < 2 or x>6 x > 6 .

Thus, the negative area of the parabola is for x<2 x < 2 or x>6 x > 6 , matching choice 2.

Answer

x < 2 o x > 6