Centuries: 1st century - 2nd century - 3rd century
Decades: 70s - 80s - 90s - 100s - 110s - 120s - 130s - 140s - 150s - 160s - 170s
120 121 122 123 124 125 126 127 128 129
Events:
... + \left( \frac{b}{a} \right) x + \frac{c}{a}=0 </math> which is equivalent to <math>x^2+\frac{b}{a}x=-\frac{c}{a}.</math> Th ...