SOLUTION: if on root of the equation 2x^2-kx+64=0 is twice the other root, then find the value of k

Question 763902: if on root of the equation 2x^2-kx+64=0 is twice the other root, then find the value of k
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
Let the roots be and .
If we knew the coefficients and was a nice round number we may solve such an equation by factoring.
Even when the roots are ugly irrational numbers, a polynomial can be written in factored form if you know the zeros.
In this case, the factored equation would be
or
Re-multiplying, we get

If that equation is equivalent to (both with for a leading coefficient),
then the other copefficientsa are also the same, so
and -->
--> -->
RELATED QUESTIONS
Given the equation kx^2+(k-1)x+2k+3=0 where k is a non-zero integer, find the value of k... (answered by josmiceli)

If one root of the equation ... 2x^2+10x+k=0 is -2, find K and the other... (answered by robertb,ewatrrr)

one root of the quadratic equation x2-kx+8=0 is negative of the other. the value of k... (answered by Edwin McCravy,Theo)

find the value of k and the other root of 4x^2 + kx + 15=0 if 5 is one of its... (answered by ikleyn)

find the value of k. x^2+kx-21=0 when one root is... (answered by checkley77)

If 1 is a root of the equation 5x^2 +kx-3=0,find the other... (answered by stanbon)

Find the value of k so that 2x^2-kx+5=0 has one real rational... (answered by HyperBrain)

for what value of k will one of the root of the equation x^-kx+8=0 be twice the other (answered by ikleyn)

given the equation Kx^2+(k+3)x+3-4k=0 find the value of k given that one root is 2 (answered by jim_thompson5910)