help? find the values of k which will make the roots of the equation real: kb^2-9b+4=0

Question

hartnn · Answer

h @Noodles24 
$\Huge \mathcal{\text{Welcome To OpenStudy}\ddot\smile} $

compare your quadratic equation with 
$Ab^2+Bb+C=0$

the roots will be equal when 
$B^2-4AC=0$

hartnn · Answer

so find A,B,C first

anonymous · Answer

A=k, B=9, C=4?

hartnn · Answer

B = -9
isn't it ?

anonymous · Answer

yes you are right, my bad

hartnn · Answer

because the 2nd term is -9b

ok, so now calculate
B^2-4AC ?

hartnn · Answer

$81 - 4\times 4\times k =0$
can you find k from here ?

anonymous · Answer

yes thank you very much, you were  a ton of help! :)

hartnn · Answer

actually, for real roots,
its $B^2-4AC >0$

hartnn · Answer

so, please solve 
$81-16k \ge 0$
and not =

anonymous · Answer

oh ok

hartnn · Answer

***$B^2-4AC \ge 0$

hartnn · Answer

let me know what you get for 'k' so that i can verify :)

anonymous · Answer

k is less than or equal to 81/16?

hartnn · Answer

good!
absolutely correct :)

anonymous · Answer

yay! thank you so much :)

hartnn · Answer

welcome ^_^

anonymous · Answer

could you help me with another problem?

anonymous · Answer

i am doing a regents review sheet and a couple are hard >_<

hartnn · Answer

sure :)
ask.

anonymous · Answer

determine the constant that must be added to the given expression to complete the square and express the resulting trinomial as the square of a binomial.

anonymous · Answer

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