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# Maths Questions Help!?

1. f(x) = x/(x-1)

Find ff(x).

I worked out ff(x) = x.

Then the question says, "What does your answer tell you about the function f?".

2. Andrea buys 100 cakes to sell in her cafe. She pays $1.80 for each cake.

On Monday she sells 60 cakes. She sells these cakes for $4.00 each.

On Tuesday she reduces the price of each cake by (1/5).

She sells 35 cakes at this reduced price.

Andrea then gives away the 5 unsold cakes.

Calculate the total profit that Andrea makes on the cakes.

Thanks!

### 2 Answers

- norcekriLv 71 decade agoFavorite Answer
1. I expect that the instructor wants you to notice a particular functional property. Assume for a moment that the inner and outer "f"s are different functions -- call the extra one "g". You've just shown that f(g(x)) = g(f(x)) = x. What does this tell you about the functions?

2. All you've done is post the problem. Where are you stuck? Simply handing you the entire answer is cheating. Compute her total cost and total revenue. Subtract. That's the profit.

- Anonymous1 decade ago
2. First you have to find out how much Andrea gained and then subtract the amount she paid for the cakes. If the answer is positive, it means that Andrea made a profit but if it's negative it means a loss.

So hear goes:

Andrea needed $180 to buy the cakes

$1.80 x 100 = $180

Andrea earns

Monday: 60 x 4= $240

Tuesday: 35 x 4/5= $28

Total amount earned= 240+28= $268

Therefore, the total profit is:

$268-$180=$88

Sorry but I don't know about the first question