(a+b)(c+d)= (a+b)(c+d)= (a+b)(c+d)= ?
Let's simplify the expression by opening the parentheses using the distributive property:(a+b)(c+d)=ac+ad+bc+bd (\textcolor{red}{a}+\textcolor{blue}{b})(c+d)=\textcolor{red}{a}c+\textcolor{red}{a}d+\textcolor{blue}{b}c+\textcolor{blue}{b}d (a+b)(c+d)=ac+ad+bc+bdTherefore, the correct answer is (a).
ac + ad+bc+bd \text{ac + ad}+bc+bd ac + ad+bc+bd