Jawabanmu

2014-03-06T20:45:31+07:00
L2 = L1 ( 1+α.Δt)
    = 80 ( 1+0,000017/'C (78'C -28'C)
    = 80 ( 1+0,000017/'C . 50'C)
    = 80 ( 1+0,00085)
    = 80 + 0,00085
L2 = 80,00085

ΔL = L2 -L1
     = 80,00085 - 80
ΔL = 0,00085
2014-03-06T20:48:35+07:00
80+(80x0,000017x60)
80+0,0816
=80,0816