Did you forget the "=y" from the original equation into which you'd substituted?
Also, did the book do the same substitution you did, or did it plug in for y instead of for x?
prove that the line with the equation and the curve with equation have no points of intersection
i started by putting the first equation into the second after making the first equation . so it became then expanded the brackets. so first i squared the first bracketed term and made it then expanded the second and made it so i was left with which then came to and used the discriminant theory to make sure it came to less than 0. i came up with for the discriminant. so -80 was the discriminant. but my book says its -39. can someone explain where i went wrong with this? thanks