# Math Help - proof - please help

1. ## proof - please help

Prove that :

(a+b)(c+d)=ac+ad+bc+bd

I'd be very greatful

2. (a+b)(c+d)=(a+b)c+(a+b)d=ac+bc+ad+bd

3. Originally Posted by alternative
Prove that :

(a+b)(c+d)=ac+ad+bc+bd

I'd be very greatful
See attachment - I think it's pretty obvious that the area of the large rectangle (outlined in black) equals the sum of the areas of all the smaller rectangles.

Therefore

$(a + b)(c + d) = ac + ad + bc + bd$.