SAT Subject Test Mathematics Level 1

a^2     +   2ab +   b^2     =   (a  +   b)^2

Quadratic Formula

If ax^2 + bx + c = 0, then:

Inequalities and Absolute Value

For all n   >   0,

if  |x| <   n,  then

−n  <   x   <   n;

if  |x| >   n,  then

x   <   −n  or  x   >   n.