f(5) means to replace x in the equation with 5 then solve.
f(x) = x^2 +2x
f(5) = 5^2 + 2(5)
f(5) = 25 +10
f(5) = 35
The answer is D)35
7 guests
It costs 5 dollars per guest, so divide 35 by 5
Questions like this ("how much higher is x than y?") are answered by computing the ratio of the two quantities.
In fact, for example, the answer to "how much higher is 10 than 5?" is 2, because 10:5 = 2, and indeed 10 is twice as much as 5.
So, we have

So, the melting temperature of platinum is about one time and a half higher than the melting temperature of gold.
Answer:
Cos x = 1 -
+
-
+ ...
Step-by-step explanation:
We use Taylor series expansion to answer this question.
We have to find the expansion of cos x at x = 0
f(x) = cos x, f'(x) = -sin x, f''(x) = -cos x, f'''(x) = sin x, f''''(x) = cos x
Now we evaluate them at x = 0.
f(0) = 1, f'(0) = 0, f''(0) = -1, f'''(0) = 0, f''''(0) = 1
Now, by Taylor series expansion we have
f(x) = f(a) + f'(a)(x-a) +
+
+
+ ...
Putting a = 0 and all the values from above in the expansion, we get,
Cos x = 1 -
+
-
+ ...