Who can solve the following math problems?1.2.3 (b
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解决时间 2021-02-07 23:43
- 提问者网友：疯子也有疯子的情调
- 2021-02-07 07:21
Who can solve the following math problems?1.2.3 (b
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- 五星知识达人网友：思契十里
- 2021-02-07 08:49
1.2.3(b)let D(n) be the final answerwe haveD(n)=aD(n-1)-D(n-2)D(1)=aD(2)=a^2-1(c)let D(n) be the final answerwe haveD(n)=aD(n-1)+(b^2)[(a+b)^(n-2)]D(1)=a1.3.4if a+b+c=0then,(x,y)=(1,1) satisfied all three equations,which means these three line pass the point(1,1).if these lines pass one pointthen,ax+by+c=0bx+cy+a=0since lines are distinguished each other,ac-b^2 != 0x=(-c^2+ab)/(ac-b^2)y=(-a^2+bc)/(ac-b^2)from the last equationc(-c^2+ab)/(ac-b^2)+a(-a^2+bc)/(ac-b^2)+b=0we geta^3+b^3+c^3-3abc=0that is(a+b+c)(a^2+b^2+c^2-ab-bc-ac)=0(a+b+c)0.5((a-b)^2+(b-c)^2+(c-a)^2)=0since a=b=c can not be reached,otherwise three lines are actually one line,0.5((a-b)^2+(b-c)^2+(c-a)^2)>0so a+b+c=0
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- 1楼网友：夜风逐马
- 2021-02-07 09:32
哦，回答的不错
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