2a+6b-3(a+3b) raised to the power of 2

solve with steps

First simplify given expression

2a+6b-3(a+3b).... first remove parentheses
=2a+6b-3a-9b .... group like terms
=2a-3a +6b-9b .... sum like terms
=-a-3b
=-(a+3b)

Square expression
[-(a+3b)]^2 .... ^2 means raise to 2nd power
=(-1)^2 (a+3b)^2
=(a+3b)^2 .... use identity (x+y)^2=x^2+2xy+y^2
=a^2+6b+9b^2