Answer:
r^2 + 6rs - 4rd - 2d^2 + 3s^2
Step-by-step explanation:
3(r+s)^2 - 2(r+d)^2
PEMDAS
parenthesis, exponents, multiplication, division, addition, subtraction
in that order
3( r^2 + 2rs + s^2 ) - 2(r^2+ 2rd + d^2)
3r^2 + 6rs + 3s^2 - 2r^2 - 4rd - 2d^2
r^2 + 6rs - 4rd - 2d^2 + 3s^2
