You wrote this: k(x)= x^3+1/x+1 That meansBut I'll bet you didn't mean that at all, right? I'll bet you meant this instead: At least learn this: If you are going to type a fraction all on one line, then you MUST use parentheses around the entire numerator and/or the entire denominator if either one contains more than just one letter or just one number. What you should have typed was this: k(x) = (x^3+1)/(x+1) Edwin