Find the largest integer $k$ such that the equation
5x^2 - kx + 8 - 20x^2 + 45 = 0
has no real solutions.
First, let's simplify this equation. Combining all like terms, we have
\(-15x^2-kx+53=0\)
Now, in order for the value of x to not be real, then the descriminant must be negative.
Thus, we have
\({\left(-k\right)^2-4\left(-15\right)\cdot \:53} < 0\)
Now, we simplfy solve for k. We get that
\(k^{2}-3180 < 0\\ k^2 < 3180\\ -2\sqrt{795} <2\sqrt{795}\\ -56.39 < k < 56.39\)
The largest integer k can be that fits in the range given for k is 56.
So our answer is just 56.
Thanks! :)