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Find the largest integer $k$ such that the equation
5x^2 - kx + 8 - 13x^2 + 39 = 0
has no real solutions.

 Aug 9, 2024
 #1
avatar+1926 
+1

First, let's set up a quadratic equation for x. Combining some like terms, we get

\(-8x^2-kx+47=0\)

 

Now, in order for the problem to have no real solutions, the descriminant must be less than 0. 

Thus, let's set up the descriminant to find k. 

We get that

\(k^2+1504<0\)

 

Isolating k, we get

\(k^2<-1504\)

 

However, note that k^2 cannot be negative, meaning that k^2 cannot possibly be smaller than -1504. 

Therefore, it is impossible for the equation to have no real solutions. 

 

Thanks! :)

 Aug 9, 2024
edited by NotThatSmart  Aug 9, 2024

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