using boolean law to simplify equation

Question

I need to use boolean laws to simlfy the folliwng: a) (A+B)(C+D)+(A+B)(C'+D')= what I did for a)

(A+B)(C+D)+(A+B)(C'+D')

(A+B)[(C+D)+(C'+D'))

(A+B(C+B)+(A+B)(c'+D')

(A+B(C+B)+(A+B)(c'+D') Am I correct?

b) [A'(C+D)')'(A)]+B(DC'')+(D'C')+A+CB'

What I did for b) A+(C+D)(A) + [B(DC)+(D'C'] + A + CB'

                 A[1+( c+d) + B + A + CB'

Am I correct?

Anyone can please clarify this?

Answer 1

Seems to me C and D get reduced-out:

(A+B)(C+D)+(A+B)(C'+D') =  
(A+B)((C+D)+(C'+D')) =  
(A+B)(C+D+C'+D') =  
(A+B)(C+C'+D+D') =  
(A+B)((C+C')+(D+D')) =  
(A+B)(1+1) =  
(A+B)1 =  
A+B