given a graph (that I am not sure how to put on here) find the expression f(x)=Ca^x
two points (0,2), (2,2/9)
I tried to solve it by
pluging in 2=Ca^x
I know that x=0 at Y=2
2=C1 (a^0 is 1 correct?)
2=C
plug in 2 for a in 2/9=2a^2
solve for a and get 2/3??
divide by 2
(2/9)/(2)=a^2
times the reciprocal of 2 (1/2)(2/9) gives you (2/18). sqrt that and I got 1/3
so f(x)=2(1/3)^x
not sure if it is right, but did I go about the problem correctly or is there another way to solve this?
2007-08-28 06:09:40 · 3 answers · asked by m_carl 1 in Science & Mathematics ➔ Mathematics
*Quote:
I tried to solve it by
pluging in 2=Ca^x
I know that x=0 at Y=2
2=C1 (a^0 is 1 correct?)
2=C
This is correct.
For the second part,
given (2, 2/9) as your point,
2/9 = 2*a^2
1/9 = a^2
a=1/3
so your function is
f(x)=2*(1/3)^x
You got it.
2007-08-28 06:22:51 · answer #1 · answered by Not Eddie Money 3 · 0⤊ 0⤋
f(x)=Ca^x
2= Ca^0 --> C=2
f(x) = 2a^x
2/9 = 2a^2
1/9= a^2
1/3 = a
So f(x) = 2 (1/3)^x
Right on.
2007-08-28 13:30:06 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
You did beautifully. A+++
2007-08-28 13:13:02 · answer #3 · answered by Christophe G 4 · 0⤊ 0⤋