Y = (AC-CX)/(B+X)

and i am needed to work out the uncertainty in Y.

values for these are:

Y=2.18 UNCERTAINTY UNKNOWN

A=29m Uncertainty in A denoted (Sa)=3mm

B=710mm Uncertainty in B denoted(Sb)=3mm

C=5.85mm Uncertainty in C denoted(Sc)=0.2mm

D=0.150mm Uncertainty in D denoted (Sd)=0.005mm

X=18.68m Uncertainty in X denoted (Sx)=0.005mm

using these values i used the formula:

Sy/Y = (Sc/C)+ S[(A-x)(B+x)]/[(A-x)(B+x)]

Sy/Y = (0.2/5.85) + (0.1099555934/0.3723445134)

Sy= 0.7182971382

i obtained an uncertainty of 0.7 it is very large hence i think i may have done something wrong in my calculations.

to obtain S[(A-x)(B+x)]

i did

[S(A-x)/(a-x)] + [S(B+x)/(B+x)]

=[(3mm+.005)/(29-18.68)] + [(3mm+.005)/(710+18.68)]

=0.1099555934

so can anyone please check this thanks!!!

also another simple question

Y= (AC-CX)/(B+X)

how do i derive for B, keeping everything else constant?

eg if i were to derive with respect to C, whilst keeping everything else constant i would get

: [A-X/(B+X)] .... so how do i derive with respect to B while keeping everything else constant since it is in the denomitor...

THANKS ALL