9 2 --- - a 100
9/100 - a^2
1*(a + 3/10)*(a - 3/10)
(1*(a + 3/10))*(a - 3/10)
0.09 - a^2
-(-3 + 10*a)*(3 + 10*a) ------------------------ 100
-(-3 + 10*a)*(3 + 10*a)/100
2 9 - 100*a ---------- 100
(9 - 100*a^2)/100