f(x ) = ( x -2 ) lnx
ecuatia tangentei ; y - f( 1 ) = f ' (1 ) ( x -1 )
A ( 1 , 0 )
f '( x) = lnx + ( x -2 ) /x
f '( 1) = ln1 + ( 1 -2 ) /1 = -1
tg ; y - 0 = -1 · ( x -1 )
y = -x + 1
tg : x + y - 1 =0
lim [ f(x ) - f( 1 ) ] / ( x -1 ) = definitia derivatei in punctul x=1 = f ' ( 1 ) = - 1
x->1
