Thursday, August 16, 2012

find the value of k in each of the following?a.) kx^2-6x+1=0 if the equation has real, rational, and equal roots.

a.) kx^2-6x+1=0 if the equation has real, rational, and equal
roots.


If the function has rational , real and equal roots, then
that mean delta will be 0:


We know
that:


delta = b^2 - 4ac


==>
delta = (-6)^2 - 4*k*1


==> 36 - 4k =
0


==> -4k = -36


==> k =
-36/-4 = 9


==> k = 9 


b.) 2x^2+6x+k=0 find the smallest integral value of
k, such that the equation had imaginary roots


If the function has
imaginary of (complex) roots, then delta should be less than 0 (
negative).


==> delta = b^2 -
4ac


==> delta = (6^2) - 4*2*k <
0


==> 36 - 8k <
0


==> -8k <
-36


==> k >
-36/-8


==> k > 9/2


Then
the smallest integer is the first integer that comes after 9/2


9/2 =
4.5 , then the next integer s 5


Then k = 5 is the
smallest integer so the equation has complex roots.

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