- #1

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How do I get D by itself? This one's got me baffled

[(A - D)^P] / [(B - D)^R] = (C - D)^(P - R)

[(A - D)^P] / [(B - D)^R] = (C - D)^(P - R)

- #1

- 23

- 2

How do I get D by itself? This one's got me baffled

[(A - D)^P] / [(B - D)^R] = (C - D)^(P - R)

[(A - D)^P] / [(B - D)^R] = (C - D)^(P - R)

- #2

SteamKing

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Take a lotta logs and see if anything shakes out.How do I get D by itself? This one's got me baffled

[(A - D)^P] / [(B - D)^R] = (C - D)^(P - R)

- #3

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Ha ha ha! I've been to the bathroom enough times while trying to figure this out.Take a lotta logs and see if anything shakes out.

- #4

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- #5

SteamKing

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Unknown exponents of what?

- #6

- 23

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My exponents, P and RUnknown exponents of what?

- #7

fresh_42

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- #8

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I don't know what economic indexes are, but I am trying to solve for two unknowns in the common equation: V(t) = Vf + (Vi - Vf)*e^(-t/T) where Vf and T are unknown. I am trying to fit this curve to data points that I have collected.

- #9

SteamKing

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That's a completely different equation than what you had in the OP.I don't know what economic indexes are, but I am trying to solve for two unknowns in the common equation: V(t) = Vf + (Vi - Vf)*e^(-t/T) where Vf and T are unknown. I am trying to fit this curve to data points that I have collected.

- #10

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I want to fit the curve to three points, one point gives my Vi, the other two are my different V(t)s. I simplified to get: T = -t/[ln((V(t) - Vf)/(Hi - Hf))]. Now I can set two equations equal to each other: -ta/[ln((V(ta) - Vf)/(Hi - Hf))] = -tb/[ln((V(tb) - Vf)/(Hi - Hf))].That's a completely different equation than what you had in the OP.

This simplified to [(H(ta) - Hf)/(Hi - Hf)]^tb = [(H(tb) - Hf)/(Hi - Hf)]^ta. Then [(H(ta) - Hf)^tb]/[(H(tb) - Hf)^ta] = (Hi - Hf)^(tb-ta)

- #11

WWGD

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It would help if you could Tex this, making it easier to read.

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