Найдем производную y = x ^ 2 / cos x ; Производная у = ( x ^ 2 / cos x ) \' = ( x ^ 2 * cos x ^ ( - 1 ) ) \' = ( x ^ 2 ) \' * cos ^ ( - 1 ) + x ^ 2 * ( cos x ( - 1 ) ) \' = 2 * x ^ ( 2 - 1 ) * cos ^ ( - 1 ) + x ^ 2 * ( cos x ( - 1 ) ) \' = 2 * x * cos ^ ( - 1 ) + x ^ 2 * ( cos x ( - 1 ) ) \' = 2 * x * cos ^ ( - 1 ) + x ^ 2 * ( - 1 * cos x ( - 1 - 1 ) ) * ( cos x ) \' = 2 * x * cos ^ ( - 1 ) + x ^ 2 * ( - 1 * cos x ( - 1 - 1 ) ) * ( cos x ) \' = 2 * x * cos x ^ ( - 1 ) + x ^ 2 * ( - 1 * cos x ^ ( - 1 - 1 ) ) * ( - sin x) = 2 * x / cos x - x ^ 2 * ( cos x ^ ( - 2 ) ) * ( - sin x) = 2 * x / cos x - x ^ 2 * sin x / cos x ^ 2 = ( 2 * x * cos x - x ^ 2 * sin x ) / cos x ^ 2.