Question 49295
<pre><font size = 5><b>if ax²+bx+c=0, where a, b, and c are integers 
and its two solutions have to be rational numbers,
then b^2-4ac=?

(1)3 (2)6 (3) 36 (4) 63
and please show me how you got the answer

The quadratic formula is

                  ______ 
            -b ± <font face = "symbol">Ö</font>b²-4ac
        x = —————————————
                2a 

which gives the solutions to ax²+bx+c = 0

The values will be rational only if what's under the square root radical,
namely the discriminant b²-4ac, is a perfect square.  

Edwin</pre></font></b>