Math Functions fx questions
If f(x) = Y, then does that mean f(x) IS Y?
example: f(x) = 3x + 2 ; Y = 3x + 2, both are equal?
What does f(3) = 2x + 1 mean? Is Y equal to 3 or 2x +1 ?
How do you find f(3) = 2x + 1 on a graph? Is "f(3) the Y variable? What is the X variable?
Thanks. I'm having a difficult time understanding what functions are. The whole f(x) thing confuses me
December 9, 2012
7 Comments • Newest first
Sure, we can say that. I won't tell you because I don't see a point in revealing that o_O. I figure that some people on here are good and math and willing to help, which they are, so that is why I asked. My age/grade doesn't mean anything relevant to my honest questions.
Okay, I guess I can put that to memory and accept it is the way it is.
How would I solve f(f(6) with the linear equation Y=-5+8x ?
I guess f(6) would be x = 6 so I would put that in the equation and get Y to be 43. Then I have f(43) ?
f(x) is pretty much y in a fancy way
f(3) is when you plug 3 into every x in the equation
@above it just the way it is, idk why don't ask me but that how i was taught
That makes more sense!
I'll make up some problem to see if I do it correctly:
f(x) = 5x
When x=1, y=5.
(1,5) would be the solution
f(4) = 25x - 5
(4, 95)
Thanks.
How about for the transformation/translation rules:
f(x + a) is f(x) shifted left a units
f(x - a) is f(x) shifted right a units
Why is that? I thought right on the numberline is positive?
Yes, the equal sign means the two are the same.
f(3) means that wherever x would normally be, a 3 is substituted instead. So if f(x)= 2x+1, f(3)=2(3)+1=7.
On a graph, f(x) is the function. When you have 3 as the x co-ordinate, f(3) is used to find the y co-ordinate. So again, if f(x)=2x+1, when x=3, f(3)=7. Therefore, the point (3,7) lies on the graph.
3 is the X variable, Y is 2(3)+ 1 = 7 so (3,7)
If it's f(3), you just plug it into the equation, i.e f(3) = 2(3) + 1