1) y = tgx
y' = (tgx)'= 1/(cos²x)
y'' = ( 1/(cos²x) )' = ( (-2) × (-sinx) ) / (cos³x) = 2 tgx / cos²x
1) y = tgx
y' = (tgx)'= 1/(cos²x)
y'' = ( 1/(cos²x) )' = ( (-2) × (-sinx) ) / (cos³x) = 2 tgx / cos²x