Question 919308
<pre>
Since the square roots of 196 are +14 and -14, 

x<sup>2</sup> + kx + 196 = 0

to be a perfect square trinomial, it would have to factor as

(x+14)<sup>2</sup> = 0  or (x-14)<sup>2</sup> = 0

or

(x+14)(x+14) = 0 or (x-14)(x-14) = 0  

which when multiplied out gives

x<sup>2</sup> + 28x + 196 = 0 or x<sup>2</sup> - 28x + 196 = 0

So k would have to be +28 or -28

Edwin</pre>