<p>Commissars used to lead the masses into combat. Nowadays they just manipulate the masses (see the first post or “[Commissar</a> readies the attack”](<a href=“http://www.lshmwaco.org/albums/Mad_baron/photos/photo4.html]Commissar”>Commissar readies the attack)). 
Glitches in a book (SparkNotes?) should not be impedimental.
You could’ve plugged your and TI’s x and y in both equations and see which values work better. (You are right - scrolling does not cut it.) 
</p>
<p>You may not trust your doctor, but you should trust your calculator!
I suspect that what you (and a poor book author) did by hand was getting from
x^2 - ((2x-5)/3)^2 = 77 to
5x^2 +20x + 25 = 693 instead of
5x^2 + 20x - 25 = 693.</p>
<p>Try this on your trustworthy TI:
Set “Exact/Approx” MODE to “AUTO”.
Define y = (2x - 3)/5 (use F4 and 1),
x^2 - y^2 - 77 = 0
“ENTER”
solve(
“UP arrow”
“ENTER”
“,x)”
“DIAMOND”
“ENTER”.</p>
<p>Don’t forget to clean up your room with F6.</p>
<p>This should help (I hope). ;)</p>