Question 1205621
<br>
f(x) is the equation of a straight line only if the coefficient of the x^2 term is zero.  We don't care about the other terms.<br>
The function is<br>
f(x) = x^2 + ... + k(x^2+...) = (x^2 + kx^2) + ... = (1+k)x^2 + ...<br>
So<br>
1+k = 0
k = -1<br>
ANSWER: -1<br>