abxxx2+a2

a+b

a+b¯

x+x+x+xktimes

a+b

abcd

-b±b2-4ac2a

(-b±(b^2-4ac))/2a

a+bn=k=0nnkakbn-k

(a+b)^n=_(k=0)^n▒(n¦k) a^k b^(n-k)