大学学部レベル質問スレ 27単位目

f'(x) := d/dx f(x)
log'(x) = 1/x (∵ def.)
log'(xy) = 1/x (∵ low of diff. of comp. )
( log(x) + log(y) )' = 1/x
log(1y) = log(y)
log(1)+log(y) = log(y)