Determine the X-axis Intersection Points of the Quadratic Function: y = (x-1)(2x+1)

Question

Determine the points of intersection of the function

y=(x1)(2x+1) y=(x-1)(2x+1)

With the X

Video Solution

Solution Steps

00:00 Find the intersection points with the X-axis
00:03 At the intersection point with the X-axis, the Y value must = 0
00:07 Set Y = 0 and solve to find X values
00:13 Find what zeroes each factor in the multiplication
00:32 This is one solution
00:57 This is the second solution
01:10 Let's verify that each solution truly zeroes the Y value
01:36 This solution zeroes
01:50 Let's check the second solution
02:15 This solution also zeroes, these are the intersection points with the X-axis
02:24 And this is the solution to the question

Step-by-Step Solution

To find the points of intersection with the x-axis for the function y=(x1)(2x+1) y = (x-1)(2x+1) , we must determine when y=0 y = 0 .

Using the zero-product property, set each factor equal to zero separately:

  • x1=0 x - 1 = 0
  • 2x+1=0 2x + 1 = 0

Solving the first equation, x1=0 x - 1 = 0 :
Add 1 to both sides:
x=1 x = 1 .

Solving the second equation, 2x+1=0 2x + 1 = 0 :
Subtract 1 from both sides:
2x=1 2x = -1 .
Divide both sides by 2:
x=12 x = -\frac{1}{2} .

The solutions are the x-intercepts of the function. Therefore, the points of intersection are (1,0) (1, 0) and (12,0) \left(-\frac{1}{2}, 0\right) .

Thus, the points of intersection on the x-axis are (12,0)(- \frac{1}{2}, 0) and (1,0)(1, 0).

Answer

(12,0),(1,0) (-\frac{1}{2},0),(1,0)