How do you expand (2x+9)^2?

(2x+9)² = (2x+9)(2x+9) Use FOIL to expand these brackets: First - (2x+9)(2x+9) --> 4x² Outside - (2x+9)(2x+9) --> 4x² + 18x Inside - (2x+9)(2x+9) --> 4x² + 18x + 18x Last - (2x+9)(2x+9) --> 4x² + 18x + 18x + 81 Therefore, (2x+9)(2x+9) = 4x² + 18x + 18x + 81 = 4x² + 36x + 81