How can I reverse this equation as I am trying to find the value of z if is x is known
at the moment the equation works out the value of x and is as follows:
x = a + (z - d) * (b - a)/ (c - d)
now I know the value of x, I can populate the rest of the values but now i want to work out a new value of x but this leads me to not know what the change in value of z is, so how do I reverse the equation to find this out??
x = is known
a = is known
b = is known
c = is known
d = is known
z = this is the value I need to work out
can anyone help or is this never going to work??
abeintot ;)
at the moment the equation works out the value of x and is as follows:
x = a + (z - d) * (b - a)/ (c - d)
now I know the value of x, I can populate the rest of the values but now i want to work out a new value of x but this leads me to not know what the change in value of z is, so how do I reverse the equation to find this out??
x = is known
a = is known
b = is known
c = is known
d = is known
z = this is the value I need to work out
can anyone help or is this never going to work??
abeintot ;)
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It's hard to tell if you mean
x = a + [(z - d) * (b - a)/ (c - d)]
or
x = [a + (z - d) * (b - a)]/ (c - d)
I'm going to assume the first one, since that's what the equation you've written works out to.
Work it step by step
x - a = (z - d) * (b - a)/ (c - d)
(x - a) * (c - d) = (z - d) * (b - a)
[(x - a) * (c - d)] / (b - a) = z - d
d + {[(x - a) * (c - d)] / (b - a)} = z
x = a + [(z - d) * (b - a)/ (c - d)]
or
x = [a + (z - d) * (b - a)]/ (c - d)
I'm going to assume the first one, since that's what the equation you've written works out to.
Work it step by step
x - a = (z - d) * (b - a)/ (c - d)
(x - a) * (c - d) = (z - d) * (b - a)
[(x - a) * (c - d)] / (b - a) = z - d
d + {[(x - a) * (c - d)] / (b - a)} = z
-
You mean rearrange the following in terms of “z”
x = a + (z - d) * (b - a)/ (c - d)
HOWEVER – there is some confusion
Look at HOW its been written.
Do you mean x = [ a + (z - d) * (b - a) ] / (c - d)
OR x = a + (z - d) * [ (b - a)/ (c - d) ]
In the future use brackets more to “package-up” the variables since how it is written is open to some confusion.
x = a + (z - d) * (b - a)/ (c - d)
HOWEVER – there is some confusion
Look at HOW its been written.
Do you mean x = [ a + (z - d) * (b - a) ] / (c - d)
OR x = a + (z - d) * [ (b - a)/ (c - d) ]
In the future use brackets more to “package-up” the variables since how it is written is open to some confusion.