(1) an=a1+(n-1)d (2) R=r1+r2/r1*r2 r2rt (1)求d (2)还有这个求r2跟物理没关系纯_数学解答

(1) an=a1+(n-1)d (2) R=r1+r2/r1*r2 r2
rt (1)求d (2)还有这个求r2
跟物理没关系纯粹求数我是真的一点不会啊

人气：420 ℃　时间：2020-05-27 23:17:33

解答

(1) an=a1+(n-1)d
(n-1)d=an-a1
d=(an-a1)/(n-1)
(2) R=r1+r2/r1*r2
Rr1r2=r1+r2
Rr1r2-r2=r1
(Rr1-1)r2=r1
r2=r1/(Rr1-1)