Decades: 950s BC 940s BC 930s BC 920s BC 910s BC - 900s BC - 890s BC 880s BC 870s BC 860s BC 850s BC
... symbol <math>\pm \sqrt {b^2-4ac}</math> in the formula should be understood as "either of those element(s) of the field whose square equals b2 - 4ac". In ...