Solve y = x² - 49: Finding X-Intercepts of a Quadratic Function

Question

Determine the points of intersection of the function

y=x249 y=x^2-49

With the X

Video Solution

Solution Steps

00:00 Find the intersection point of the function with the X-axis
00:03 At the intersection point with the X-axis, Y equals 0
00:07 Substitute Y=0 in our equation and solve to find the intersection point
00:12 Isolate X
00:18 Extract the root
00:25 Remember when extracting a root there are 2 solutions (positive and negative)
00:32 These are the X values
00:36 Y = 0 as we substituted at the beginning
00:42 And this is the solution to the problem

Step-by-Step Solution

To determine the points of intersection of the function y=x249 y = x^2 - 49 with the x-axis, we set y=0 y = 0 . This gives us the equation:

x249=0 x^2 - 49 = 0

We can solve this equation by factoring or using the square root method:

  • Recognize x249 x^2 - 49 as a difference of squares since 49=72 49 = 7^2 .
  • The equation can be rewritten and factored as: (x7)(x+7)=0 (x - 7)(x + 7) = 0 .

Setting each factor equal to zero gives:

x7=0 x - 7 = 0 or x+7=0 x + 7 = 0

This simplifies to:

x=7 x = 7 or x=7 x = -7

Thus, the points of intersection are where the function crosses the x-axis, at the coordinates (7,0) (7, 0) and (7,0) (-7, 0) .

Referring to the given answer choices, the correct choice is:

(7,0),(7,0)(7, 0), (-7, 0)

Therefore, the points of intersection of the function y=x249 y = x^2 - 49 with the x-axis are (7,0)(7, 0) and (7,0)(-7, 0).

Answer

(7,0),(7,0) (7,0),(-7,0)