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Find the range of values of k for which x^2 +k(x+2) +3(x+1) >0 for all real values of x.
try to solve as you usually do with double brackets!
>0 take as = 0 but do write >0 when solving
try to get it in the form ax^2+bx+c>0 (quadratic equation), determine its discriminant Δ which is a function of k. Then solve Δ<0
Furthermore, working with double brackets keep in mind that not only the product of two positive numbers is greater than zero, but also the product of two negative ones.
(edited 8 years ago)
Reply 3
Original post by fatima1998
try to solve as you usually do with double brackets!
>0 take as = 0 but do write >0 when solving


This can lead to problems with quadratic inequalities.
Original post by B_9710
This can lead to problems with quadratic inequalities.


but isn't this just a simple algebra but they put that sign to make it complicated!
Reply 5
Original post by fatima1998
but isn't this just a simple algebra but they put that sign to make it complicated!


Not at all!
Original post by Zacken
Not at all!


oops!! i misunderstood the question :biggrin:
i thought the question is to find the value of x but it's values of the k :redface:

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