Write missing monomials to make an identity: A) (.....+2a)^2=.....+12ab+4*.... B) (3x+.....)^2=....*x^2+.....+49y^2

Answer 1

12 = 2(2*3) so (3b+2a)^2 = 9b^2 + 12ab + 4a^2
now you try the other. note that (3x)^2 = 9x^2 and (7y)^2 = 49y^2