Function Evaluation

[nycmath]

Consider the function f(x) = x/(x + 4).

A. Is the point (1, 1/4) on the graph of f?

B. If x = - 2, what is f(x)? What point is on the graph of f?

C. If f(x) = 2, what is x? What point is there n the graph of f?

[Eigenvalue]

f(x)=[tex]\frac{x}{x+4}[/tex]

A. Let x=1 and f(x)=0.25
0.25[tex]\ne[/tex]1/5
No, the point is not on f(x)

B. Let x=-2
f(x)=[tex]\frac{-2}{4-2}[/tex]=[tex]\frac{-2}{2}[/tex]=-1
f(x), or the y value, is -1

C.Let f(x)=2
2=[tex]\frac{x}{x+4}[/tex]
Multiply both sides by x+4
2(x+4)=x
2x+8=x
x=-8
The x- value would be -8

[nycmath]

f(x)=[tex]\frac{x}{x+4}[/tex]

A. Let x=1 and f(x)=0.25
0.25[tex]\ne[/tex]1/5
No, the point is not on f(x)

B. Let x=-2
f(x)=[tex]\frac{-2}{4-2}[/tex]=[tex]\frac{-2}{2}[/tex]=-1
f(x), or the y value, is -1

C.Let f(x)=2
2=[tex]\frac{x}{x+4}[/tex]
Multiply both sides by x+4
2(x+4)=x
2x+8=x
x=-8
The x- value would be -8

You have a natural gift for mathematics. Very cool.