• Nov 19th 2008, 04:04 PM
live_laugh_luv27
A quadratic equation x^2 + bx + c = 0 has complex roots 3+6i and 3-6i. Find the values of b and c.

Thank you for any help!
• Nov 19th 2008, 04:09 PM
Jhevon
Quote:

Originally Posted by live_laugh_luv27
A quadratic equation x^2 + bx + c = 0 has complex roots 3+6i and 3-6i. Find the values of b and c.

Thank you for any help!

hint: the coefficients of the x-squared term in the quadratic is 1, thus the quadratic is given by \$\displaystyle (x - r_1)(x - r_2)\$, where \$\displaystyle r_1\$ and \$\displaystyle r_2\$ are the two roots of the equation
• Nov 19th 2008, 04:19 PM
live_laugh_luv27
Quote:

Originally Posted by Jhevon
hint: the coefficients of the x-squared term in the quadratic is 1, thus the quadratic is given by \$\displaystyle (x - r_1)(x - r_2)\$, where \$\displaystyle r_1\$ and \$\displaystyle r_2\$ are the two roots of the equation

So, would you do (1-(3+6i )) and (1-(3-6i))??
• Nov 19th 2008, 04:21 PM
Jhevon
Quote:

Originally Posted by live_laugh_luv27
So, would you do (1-(3+6i )) and (1-(3-6i))??

i have no idea how you got that

to follow up on what i said, start with \$\displaystyle (x - 3 - 6i)(x - 3 + 6i)\$

now multiply out and you can find b and c
• Nov 19th 2008, 04:25 PM
live_laugh_luv27
Quote:

Originally Posted by Jhevon
i have no idea how you got that

to follow up on what i said, start with \$\displaystyle (x - 3 - 6i)(x - 3 + 6i)\$

now multiply out and you can find b and c

Thank you so much for your help!!
• Nov 19th 2008, 04:28 PM
Jhevon
Quote:

Originally Posted by live_laugh_luv27
Thank you so much for your help!!

you're welcome (Sun)

• Nov 19th 2008, 04:29 PM
live_laugh_luv27
Quote:

Originally Posted by Jhevon
you're welcome (Sun)

b = -9, c=45
• Nov 19th 2008, 04:33 PM
Jhevon
Quote:

Originally Posted by live_laugh_luv27
b = -9, c=45

b is incorrect
• Nov 19th 2008, 04:36 PM
live_laugh_luv27
-6 !!!!!!!!!!!
• Nov 19th 2008, 04:37 PM
Jhevon
Quote:

Originally Posted by live_laugh_luv27
-6 !!!!!!!!!!!

um, yes...!!!!!!!!!!!!
• Nov 19th 2008, 04:39 PM
live_laugh_luv27
Quote:

Originally Posted by Jhevon
um, yes...!!!!!!!!!!!!