MHB When two resistors are in parallel....(rational functions)

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When two resistors, s and t, are in parallel, their combined resistance R is calculated using the formula 1/R = 1/s + 1/t. To determine the change in resistance when s is increased by 1 unit and t is decreased by 1 unit, the initial resistance R_i is calculated first. The final resistance R_f is then found by substituting s+1 for s and t-1 for t in the resistance formula. The change in resistance is computed as ΔR = R_f - R_i. This approach effectively illustrates how variations in resistor values impact overall resistance in parallel circuits.
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When two resistors, $$s$$ and $$t$$, are connected in parallel, their combined resistance, $$R$$, is given by $$\frac{1}{R}$$ = $$\frac{1}{s}$$ + $$\frac{1}{t}$$

If $$s$$ is increased by 1 unit and $$t$$ is decreased by 1 unit, what is the change in $$R$$?(I'm not really sure how to do this...help would be appreciated! Thanks.)
 
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I would first solve for $R$ and call this $R_i$, or the initial resistance. The substitute $s+1$ for $s$ and $t-1$ for $t$ in that expression and call that $R_f$, or the final resistance. Then compute the change in the resistance by:

$$\Delta R=R_f-R_i$$
 
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