Answer:
yes they form a proportion
Given functions are


The total number of ducks and swans in the lake after n months can be determined by adding the functions s(n) and d(n).





Taking 2 as common, we get

Hence The total number of ducks and swans in the lake after n months is
Answer:
Step-by-step explanation:
AB^2 = HB^2 + AH^2 => AB = 15cm
Ta co cong thuc: 1/AH^2 = 1/AB^2 + 1/AC^2 => AC=20cm
Vay SABC= 1/2 .AB.AC = 1/2 .15.20=150cm^2
There are many like
1(10)+10-1=19
18+1=19
30-11=19
15+4=19
Hope this help!!