Question

Вот эти 3 помогите)
По алгебре)

Answer 1

(a-b)/(a+b) * (a/5 + b/5) = (a-b)/(a+b) * (a+b)/5 =  (a-b)/5
(1 + 1/a) : (1 - 1/a) = (a+1)/a : (a-1)/a = (a+1)/(a-1)
( 6/(a-b) - 5/(a+b) ) * (a-b)/(a+11b) = ( 6(a+b)-5(a-b) )/ ( (a-b)(a+b) ) * (a-b)/(a+11b) = (6a+6b-5a+5b)/ ( (a-b)(a+b) ) * (a-b)/(a+11b) = (a+11b)/ ( (a-b)(a+b) ) * (a-b)/(a+11b) = 1/(a+b)