Question

i need quick help

Answer 1

http://prntscr.com/l99kd6

where did they get the other 4 ?

Answer 2

@Shadow

Answer 3

completing the square\[\large\rm (\color{reD}{a}\color{orange}{-}\color{blue}{b})^2 = \color{red}{a^2} \color{orange}{-}\color{black}{2}\color{red}{a}\color{blue}{b}\color{orange}{+}\color{blue}{b^2}\]

Answer 4

so for your question b is 2
and it is negative
so -2 times -2 or (-2)^2=4