â« x*cos(x/2) dx = 2â« x*cos(x/2) d(x/2) = 2â« x dsin(x/2)
= 2xsin(x/2) - 2â« sin(x/2) dx
= 2xsin(x/2) - 4â« sin(x/2) d(x/2)
= 2xsin(x/2) + 4cos(x/2) + C
â« x�0�5â(x-3) dxï¼ç¨ç¬¬ä¸ç±»æ¢å
æ³è¾å¥½
令u = â(x-3)ï¼du = dx/[2â(x-3)]
åå¼= 2â« u�0�5(u�0�5+3)�0�5 du
= 2â« (u^6+6u^4+9u�0�5) du
= (2/7)u^7 + (12/5)u^5 + 6u�0�6 + C
= (2/7)(x-3)^(7/2) + (12/5)(x-3)^(5/2) + 6(x-3)^(3/2) + C
= (2/35)(5x�0�5+12x+24)(x-3)^(3/2) + C
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