（1）R=(R1*R2)/(R1+R2)(注：R不等于R2）,求R1
问题描述：
（1）R=(R1*R2)/(R1+R2)(注：R不等于R2）,求R1
（2）已知（S/V）-S/（V+2)=1,求S
答
原式=R(R1+R2)=R1R2 =RR1+RR2=R1R2 RR2=R1R2-RR1 RR2=R1(R2-R) RR2/(R2-R)=R12: S(V+2)/V(V+2)-SV/V(V+2)=1[S(V+2)-SV]/V(V+2)=12S/V(V+2)=12S=V(V+2) S=V(V+2)/...