1/R=1/R2 / 1/R1
两边乘1/R1得
1/R*R1=1/R2
所以R2=1除以1/R*R1
=R*R1
回答完毕,拿分走人.是1/R=1/R2 + 1/R1，不是除啊sorry，看错了谢谢采纳正确答案：两边同乘以RR1R2得R1R2=RR1+RR2移项得R1R2-RR2=RR1整理得（R1-R）R2=RR1系数化为一得R2=RR1/R1-R