What’s the value of x?

6*15 = 5(x+5)

90 = 5x + 25

65 = 5x

x = 13

Step-by-step explanation:

I've gone ahead and labeled some points.

There is a formula that says PA*PB = PC*PD, this is what you use.  If you would like me to show why this works I would be happy to.

So what we have is PA = 6, PB = 9+6 = 15, PC = 5 PD = 5+x so let;s writ ethe formula with these values

6*15 = 5(x+5)

90 = 5x + 25

65 = 5x

x = 13

EDIT: Here is the explanation for the formula

If you form triangles PCB and PAD you can find angle D and angle B are the same, because they are inscribed angles that intersect the same arc of the circle.  Also angle P is the same on both triangles since they are the same angle, so this means both triangles are similar.

This means DA is similar to BC, AP is similar to CP and PD is similar to PB. Similar sides means if you can multiply one side by a number to get to its similar side, then you can multiply all sides by that value to get all sides of that similar triangle.  

This also means if you divide one side by its similar side you get the scale value, so this means if you do it to two different sets of similar sides you get the same number

6mm^3 or .6cm^3

      216

      /   \

  36     6

  /   \     /

6     6   6

factor trees are nice.

when functions are first introduced, you will probably have some simplistic "functions" and relations to deal with, usually being just sets of points. these won't be terribly useful or interesting functions and relations, but your text wants you to get the idea of what the domain and range of a function are. small sets of points are generally the simplest sorts of relations, so your book starts with those.

step-by-step explanation:

state the domain and range of the following relation. is the relation a function?

{(2, –3), (4, 6), (3, –1), (6, 6), (2, 3)}

the above list of points, being a relationship between certain x's and certain y's, is a relation. the domain is all the x-values, and the range is all the y-values. to give the domain and the range, i just list the values without duplication:

domain: {2, 3, 4, 6}

range: {–3, –1, 3, 6}

(it is customary to list these values in numerical order, but it is not required. sets are called "unordered lists", so you can list the numbers in any order you feel like. just don't duplicate: technically, repetitions are okay in sets, but most instructors would count off for this.)

while the given set does indeed represent a relation (because x's and y's are being related to each other), the set they gave me contains two points with the same x-value: (2, –3) and (2, 3). since x = 2 gives me two possible destinations (that is, two possible y-values), then this relation is not a function.

note that all i had to do to check whether the relation was a function was to look for duplicate x-values. if you find any duplicate x-values, then the different y-values mean that you do not have a function. remember: for a relation to be a function, each x-value has to go to one, and only one, y-value.

state the domain and range of the following relation. is the relation a function?

{(–3, 5), (–2, 5), (–1, 5), (0, 5), (1, 5), (2, 5)}

i'll just list the x-values for the domain and the y-values for the range: