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Найти частные производные первого и второго порядка

z`(x)=3x²/cos²(x³+y²)z`(y)=2y/cos²(x³+y²)z``(xx)=[6x*cos²(x³+y²)+3x²*2cos(x³+y²)*sin(x³+y²)*3x²]/cos^4(x³+y²)==[6x*cos²(x³+y²)+9x^4sin(2x³+2y²)]/cos^4(x³+y²)z``(xy)=[3x²*2cos(x³+y²)*sin(x²)*2y]/cos^4(x³+y²)==6x²y*sin(2x³+2y²)/cos^4(x³+y²)z``(yx)=[2y*2cos(x³+y²)*sin(x³+y²)*2y]/cos^4(x³+y²)==2y²*sin(2x³+2y²)/cos^4(x³+y²)z``(yy)=[2cos²(x³+y²)+2y*2cos(x³+y²)*sin(x³+y²)*2y]/cos^4(x³+y²)==[2cos²(x³+y²)+4y²*sin(2x³+2y²)]/cos^4(x³+y²)