Answer:
-1.
Step-by-step explanation:
(tanx- secx) (tanx+ secx).
= tan^2 x + tanx sec x- tanx sec x - sec^2x
= tan^2 x - sec^2 x.
But sec^2 x = 1 + tan^2 x
so tan^2 x - sec^2 x = -1
It’s easy do 2 times 14 so it’s 28
Answer: 12 friends.
Step-by-step explanation:
the data we have is:
Mei Su had 80 coins.
She gave the coins to her friends, in such a way that every friend got a different number of coins, then we have that:
The maximum number of friends that could have coins is when:
friend 1 got 1 coin
friend 2 got 2 coins
friend 3 got 3 coins
friend N got N coins
in such a way that:
(1 + 2 + 3 + ... + N) ≥ 79
I use 79 because "she gave most of the coins", not all.
We want to find the maximum possible N.
Then let's calculate:
1 + 2 + 3 + 4 + 5 = 15
15 + 6 + 7 + 8 + 9 + 10 = 55
now we are close, lets add by one number:
55 + 11 = 66
66 + 12 = 78
now, we can not add more because we will have a number larger than 80.
Then we have N = 12
This means that the maximum number of friends is 12.
5/12 because 1/1 is a whole, 1, so all you have to do is 1 - 7/12.
