SOLUTION: Hi there! I have a question about complex numbers. We need to find k and the roots if 2x^2+8x+k=0 and the product of the roots is 4. Thank you so much for helping!

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Hi there! I have a question about complex numbers. We need to find k and the roots if 2x^2+8x+k=0 and the product of the roots is 4. Thank you so much for helping!       Log On


   

Question 1139709: Hi there!
I have a question about complex numbers. We need to find k and the roots if 2x^2+8x+k=0 and the product of the roots is 4. Thank you so much for helping!
Found 2 solutions by greenestamps, ikleyn:
Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


The product of the roots of the quadratic equation

ax%5E2%2Bbx%2Bc=0

is c%2Fa.

So in your equation, the product of the roots is k%2F2.

Since you are given that the product of the roots is 4, k is 8.

Then

2x%5E2%2B8x%2B8+=+0
x%5E2%2B4x%2B4+=+0
%28x%2B2%29%5E2+=+0

The roots are -2 and -2.

Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.

As you see from the solution of the other tutor, the roots of the equation are real numbers,

so your assumption "a question about complex numbers" is   W R O N G.

It is not for the first time I ask you: stop formulate your hypotheses about the problem, because they are always   W R O N G.

Start your post with the standard mantra "Please help me solve this problem".

With this mantra, you always will be in.

Inventing any other introduction, you always will be out, because you don't know any subject.