(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

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(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
(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

(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
原式=R(R1+R2)=R1R2
=RR1+RR2=R1R2
RR2=R1R2-RR1
RR2=R1(R2-R)
RR2/(R2-R)=R1
2: S(V+2)/V(V+2)-SV/V(V+2)=1
[S(V+2)-SV]/V(V+2)=1
2S/V(V+2)=1
2S=V(V+2)
S=V(V+2)/2

①R=(R1R2)/(R1+R2)
R1R+R2R=R1R2
R2R=R1R2-R1R
R1=R2R/(r2-r)
②等式两边同时乘以 V(V+2) 得
(v+2)S-Sv=V(V+2)
S={V(V+2) }/2

R=R*R2/(R-R2)
S=1/2V*(V+2)