Find the Area of y=(x+5)²-4: Quadratic Function Analysis

Question

Find the positive area of the function

y=(x+5)24 y=(x+5)^2-4

Video Solution

Step-by-Step Solution

To find the positive area of the function y=(x+5)24 y = (x+5)^2-4 , follow these steps:

  • Step 1: Identify when the function is greater than zero.
    We need (x+5)24>0 (x+5)^2 - 4 > 0 .
  • Step 2: Find the roots of (x+5)24=0 (x+5)^2 - 4 = 0 .
    Solving, we set: (x+5)2=4 (x+5)^2 = 4 .
  • Step 3: Solve for (x+5)2=4 (x+5)^2 = 4 .
    Take the square root on both sides: x+5=±2 x + 5 = \pm 2 .
    This gives: x+5=2 x + 5 = 2 or x+5=2 x + 5 = -2 .
    Thus, x=3 x = -3 or x=7 x = -7 .
  • Step 4: Identify intervals.
    We need to look at intervals determined by the roots: (,7) (-\infty, -7) , (7,3) (-7, -3) , and (3,) (-3, \infty) .
  • Step 5: Determine where the function is positive by testing each interval:
    - For x<7 x < -7 , choose x=8 x = -8 , then ((8)+5)24=94=5 ((-8)+5)^2 - 4 = 9 - 4 = 5 (positive).
    - For 7<x<3 -7 < x < -3 , choose x=5 x = -5 , then ((5)+5)24=04=4 ((-5)+5)^2 - 4 = 0 - 4 = -4 (negative).
    - For x>3 x > -3 , choose x=0 x = 0 , then (5)24=254=21 (5)^2 - 4 = 25 - 4 = 21 (positive).

Therefore, the positive area of the function is for x<7 x < -7 and 3<x -3 < x .

Answer

x < -7 , -3 < x