Can someone please explain this to me?

I'm not quite sure where the '6x' came from since when squaring the x and the 9, I would never understand where the #x came from though I know it's to get a quadratic. Can someone please explain how to solve similar sums and get the answer? Thank you!

write it out as (x+3)(x+3) then do x(x+3) + 3(x+3) to get your answer. ie multiply the second bracket by the first and second term in the first bracket seperatly

THIS IS THE DIFFERENCE OF 2 SQUARES. Step one = square the first (x squared)
Step TWO= Square the second term giving you 6
Step Three = Multiple it by the first term (6x)
Finally Square the last term giving you 9.

akate18—