Solve y = -27 + 3x²: Finding X-Axis Intersection Points

Question

Determine the points of intersection of the function

y=27+3x2 y=-27+3x^2

With the X

Video Solution

Solution Steps

00:00 Find the intersection points of the function with the X-axis
00:03 At the intersection point with the X-axis, Y equals 0
00:08 Substitute Y=0 in our equation and solve to find the intersection points
00:12 Isolate X
00:25 Extract the root
00:31 Remember when extracting a root there are 2 solutions (positive and negative)
00:39 These are the X values
00:42 Y = 0 as we substituted at the beginning
00:49 And this is the solution to the problem

Step-by-Step Solution

To solve for the intersection points of the function y=27+3x2 y=-27+3x^2 with the x-axis, follow these steps:

  • Step 1: Set the function equal to zero because intersections with the x-axis occur when y=0 y = 0 .
    So we solve 27+3x2=0 -27 + 3x^2 = 0 .
  • Step 2: Simplify and solve the equation.
    Start with 3x2=27 3x^2 = 27 .
  • Step 3: Divide both sides by 3 to isolate x2 x^2 .
    x2=9 x^2 = 9 .
  • Step 4: Solve for x x by taking the square root of both sides.
    Thus, x=±9 x = \pm \sqrt{9} , so x=3 x = 3 or x=3 x = -3 .

Therefore, the points of intersection are (3,0) (3, 0) and (3,0) (-3, 0) .

The correct choices from the answer list are 1: (3,0) (3,0) and 2: (3,0) (-3,0) . Therefore, answer choice 4: Answers a a and b b are correct is correct.

Answer

Answers a a and b b are correct