+900 Find the sum of all values of $k$ for which $x^2 + kx - 9x + 25 - 9$ is the square of a binomial.
+1952 Let's first combine all like terms. We have
x2+kx−9x+16x2+(k−9)x+16
Since we need this to be a difference of squares, k-9 must be 2 times the square root of 16.
Thus, we have
k−9=8k=17
So k is 17.
So our answer is 17.
Thanks! :)
