What is the quadratic equation that has the roots 3+i and 3−i ?(1 point)

Responses

x2+6x−10=0
x squared plus 6 x minus 10 equals 0

x2−6x+8=0
x squared minus 6 x plus 8 equals 0

x2+6x+10=0
x squared plus 6 x plus 10 equals 0

x2−6x+10=0

1 answer

To find the quadratic equation with roots \(3 + i\) and \(3 - i\), we can use the fact that if \(r_1\) and \(r_2\) are the roots of a quadratic equation in the form \(x^2 + bx + c = 0\), then:

  • The sum of the roots \(r_1 + r_2 = -b\)
  • The product of the roots \(r_1 \times r_2 = c\)

In this case:

  • \(r_1 = 3 + i\)
  • \(r_2 = 3 - i\)
  1. Calculate the sum of the roots: \[ r_1 + r_2 = (3 + i) + (3 - i) = 3 + i + 3 - i = 6 \]

  2. Calculate the product of the roots: \[ r_1 \times r_2 = (3 + i)(3 - i) = 3^2 - i^2 = 9 - (-1) = 9 + 1 = 10 \]

Now we will use the relationships:

  • The sum of the roots gives us \( -b = -6 \) (thus \( b = -6 \))
  • The product of the roots gives us \( c = 10 \)

Therefore, the quadratic equation is: \[ x^2 - 6x + 10 = 0 \]

The correct response is: x²−6x+10=0 (x squared minus 6 x plus 10 equals 0)