jika a log 5=x dan a log 7= y,maka a log akar 1,4=

a log √1,4 = a log (7/5)^1/2
= 1/2 a log 7/5
= 1/2 (a log 7 - a log 5)
= 1/2 (y - x)
= 1/2y - 1/2x