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Hi, So I'm stuck on a part of trig which I can't seem to wrap my head around. I'm self teaching so no teacher to ask unfortunately. The question(s) come in the form:
"Find the the max and min value of each of the following functions. In each case, give the least positive values of x at which they occur. "
Then, a function would be given. For example:
e) ##9 + sin(4x - 20)##
Another question (which I have not yet attempted) is:
f) ## \frac{30}{2+cosx}##
I thought I was understanding how to find min and max values of equations. essentially, cosx/sinx will always be between -1 and 1, so you just put both those values in for x and figure it out. That worked a few times, but when I got to ##9 + sin(4x - 20)## it didn't work at all. I also am still not sure exactly what that equation is telling me, so I feel like even when I get the question right, I'm not truly understanding why. And I have no idea whatsoever about how to find least positive value for x without graphing it.
My attempt at a solution was to do
##9 + sin(4x1 - 20)##
##9 + -16##
##9 - 16 = = -7##
And I then used the same method except with -1, to get -15.
The problem is, the book I have doesn't tell you how to solve these functions, and just gives the answers without showing how to get there.
It also doesn't tell you what each number represents, and what to do when things are in parenthesis. I know, more or less, that the 9 at the beginning means that graph moves up the y-axis 9, or at least i thought I did until I put the function in on wolframalpha, and saw that it moves up 8. I also know that the number before cos/sin tells you the amplitude, and the x will tell you the period. I don't know how to approach the problem with the -20 and with things in parenthesis.
If I'm asking too much or there is too much to cover, then a suggestion of a specific book to buy/video to watch to clear this up would be great. I use Khan Academy videos, but for trig they are not very well structured in that they cover some advanced stuff before going back over basic stuff. Also I'm from the UK so the structure of what is taught and when is very different from the US I believe.
Anyway, thanks for any help, sorry for the long-winded post.
"Find the the max and min value of each of the following functions. In each case, give the least positive values of x at which they occur. "
Then, a function would be given. For example:
e) ##9 + sin(4x - 20)##
Another question (which I have not yet attempted) is:
f) ## \frac{30}{2+cosx}##
I thought I was understanding how to find min and max values of equations. essentially, cosx/sinx will always be between -1 and 1, so you just put both those values in for x and figure it out. That worked a few times, but when I got to ##9 + sin(4x - 20)## it didn't work at all. I also am still not sure exactly what that equation is telling me, so I feel like even when I get the question right, I'm not truly understanding why. And I have no idea whatsoever about how to find least positive value for x without graphing it.
My attempt at a solution was to do
##9 + sin(4x1 - 20)##
##9 + -16##
##9 - 16 = = -7##
And I then used the same method except with -1, to get -15.
The problem is, the book I have doesn't tell you how to solve these functions, and just gives the answers without showing how to get there.
It also doesn't tell you what each number represents, and what to do when things are in parenthesis. I know, more or less, that the 9 at the beginning means that graph moves up the y-axis 9, or at least i thought I did until I put the function in on wolframalpha, and saw that it moves up 8. I also know that the number before cos/sin tells you the amplitude, and the x will tell you the period. I don't know how to approach the problem with the -20 and with things in parenthesis.
If I'm asking too much or there is too much to cover, then a suggestion of a specific book to buy/video to watch to clear this up would be great. I use Khan Academy videos, but for trig they are not very well structured in that they cover some advanced stuff before going back over basic stuff. Also I'm from the UK so the structure of what is taught and when is very different from the US I believe.
Anyway, thanks for any help, sorry for the long-winded post.