I am continuously trying to answer but it says my answer has something inappropriate! I will try in comments section!
From the double-angle identity,

we can rewritte our given equation as:

By factoring 2cosx on the left hand side, we have

This equation has 2 solutions when

From equation (A), we obtain

and from equation (B), we have

On the other hand, we can find one more solution from the original equation by substituting x=0, that is,

then, x=0 is another solution. In summary, we have obtained the following solutions:

However, the intersection of the last set is empty. So the unique solution is x=0 as we can corroborate on the following picture:
Therefore, the solution set is: {0}
I'm terrible at math, so I'm sorry if I'm totally wrong, but I'm assuming you just take the average:
20+28=48m
48/2=24m
On average, it may take them 24m if they work together.
Answer:
3.5 hours
Step-by-step explanation:
Distance = 21 miles
Speed * time
Speed * time = distance
Tom speed = 2 mph
Brian = 4 mph
Let time = t
Brian distance + Tom's distance = total distance
4t + 2t = 21
6t = 21
t = 21 / 6
t = 3.5 hours
Answer:
Step-by-step explanation:
2 + 4 > 8
6 > 8
not true