Answer:
[Vertex form]
Step-by-step explanation:
Given function:

We need to find the vertex form which is.,

where
represents the co-ordinates of vertex.
We apply completing square method to do so.
We have

First of all we make sure that the leading co-efficient is =1.
In order to make the leading co-efficient is =1, we multiply each term with -3.


Isolating
and
terms on one side.
Subtracting both sides by 15.


In order to make the right side a perfect square trinomial, we will take half of the co-efficient of
term, square it and add it both sides side.
square of half of the co-efficient of
term = 
Adding 36 to both sides.


Since
is a perfect square of
, so, we can write as:

Subtracting 21 to both sides:


Dividing both sides by -3.

[Vertex form]
Square. Because there is 2 right angles there are only 4 sides all which are perpendicular
Exchange rate refers value of a currency in another.The cost of the decorative mug is 83.98 China Yuan.
<h3>What is the exchange rate?</h3>
The term exchange rate has to do with the value of a currency in another currency. Given the fact that international trade is the mainstay of the global economy, it is important that one currency should be converted to another for the purpose of the ease of doing business.
The dollar is often the international currency for trade. Its us always necessary to convert the dollar into the local currency of the country where the business is done using the correct exchange rate.
Now If I want to convert the cost of the decorative mug to China Yuan;
I already know that;
1 US dollar = 6.4651 China Yuan
12.99 US dollar = 12.99 US dollar * 6.4651 China Yuan/1 US dollar
= 83.98 China Yuan
Hence, the cost of the decorative mug is 83.98 China Yuan.
Learn more about exchange rate:brainly.com/question/22996931
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