Perform the indicated operation. (a + b)(a - b)

a^ - b^     a squared minus b squared.

use distributive property of multiplication.  FOIL (first, outside, inside, last)

a *a = a^   - b*a= ab (or ba)  +   b*a = ba (or ab)  -  b*b= b^

a squared - ab +ab - b squared  

Negative ab and positive ab = 0 therefore you are left with

a^ - b^

  q

step-by-step explanation:

each line from a vertex to the midpoint of the opposite side is called a median. the point where the medians intersect, point q, is the centroid.

the centroid of δabc is point q.