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a=（x+2,X^2-(cosm)^2)；b=(y,y/2+sinm)；且a向量等于2倍b向量;由以上条件可以得到:x+2=2y;所以x=2y-2......(1);X^2-cos^2m=y+2sinm......(2);化简(2)可得到:x^2-y=2-(sinm-1)^2......(3);由于x,y,m为实数，所以-1=<sinm<=1,-2=<sinm-1<=0,-4=<-(sinm-1)^2<=0;所以-2=<2-(sinm-1)^2<=2......(4);由(4)及(3)可知-2=<x^2-2y<=2......(5);将(1)带入(5)得到:-2=<4y^2-9y+4<=2......(6... |
