Analyze the Quadratic y = 2x² - 4x + 2: Determining Positive and Negative Domains

Question

Find the positive and negative domains of the function below:

y=2x24x+2 y=2x^2-4x+2

Step-by-Step Solution

To solve for the positive and negative domains of the function y=2x24x+2 y = 2x^2 - 4x + 2 , we follow these steps:

  • Step 1: Find the roots of the equation using the quadratic formula. For ax2+bx+c=0 ax^2 + bx + c = 0 , the roots are found by x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} .
  • Step 2: For our specific function, identify: a=2 a = 2 , b=4 b = -4 , c=2 c = 2 .

Let's calculate the discriminant: b24ac=(4)24×2×2=1616=0 b^2 - 4ac = (-4)^2 - 4 \times 2 \times 2 = 16 - 16 = 0 .
Since the discriminant is zero, we have a repeated root, which means the graph touches the x-axis at one point.

The root is found as follows:
x=(4)±02×2=44=1 x = \frac{-(-4) \pm \sqrt{0}}{2 \times 2} = \frac{4}{4} = 1 .

This root x=1 x = 1 represents a vertex-touching parabola, with no intervals of x x such that y<0 y < 0 .

To find the positive domain (y>0 y > 0 ), we note the parabola y=2x24x+2 y = 2x^2 - 4x + 2 opens upwards (since a=2>0 a = 2 > 0 ) and only touches the x-axis at one point (1,0) (1, 0) . Thus, the positive domain is x1 x \ne 1 .

The function does not take any negative values, since it opens upwards and only touches the x-axis.

Therefore, the positive domain is x>0:x1 x > 0 :x \ne 1 and the negative domain is x<0: x < 0 : none.

In conclusion, the solution to the problem is:

x>0:x1 x > 0 :x \ne 1

x<0: x < 0 : none

Answer

x > 0 :x\ne1

x < 0 : none