SOLUTION: FIND THE DOMAIN {3X+4}

Algebra ->  Functions -> SOLUTION: FIND THE DOMAIN {3X+4}      Log On


   



Question 3850: FIND THE DOMAIN {3X+4}
Found 2 solutions by longjonsilver, khwang:
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
if roots are (4+i) and (4-i), then we can say:

x=(4+i) or x=(4-i)

so, x-(4+i)=0 or x-(4-i)=0


So, the factors are (x-(4+i))(x-(4-i))=0
hence (x-4-i)(x-4+i)=0

Now expand, to give x%5E2+-+4x+%2B+xi+-+4x+%2B+16+-+4i+-+xi+%2B+4i+-+i%5E2+=+0
x%5E2+-+8x+%2B+16+-+i%5E2+=+0
x%5E2+-+8x+%2B+16+-+%28-1%29+=+0
x%5E2+-+8x+%2B+17+=+0

So, a possible equation is y=x%5E2+-+8x+%2B+17

jon.

Answer by khwang(438) About Me  (Show Source):
You can put this solution on YOUR website!
Two roots 4+i & 4-i. (r1 & r2)

Their sum = 8 and their product is 4^2 + 1 = 17.
So, the equation is x^2 - 8x + 17 = 0 (ie x^2 - (r1+r2)x + r1 r2 =0
Forget any any other way of solutions more than two lines about this kind of
baby level questions.
Also, there is no any reason you did not know the typing '+' sign.

Kenny