平面内给定三个向量a=(3,2),b=(-1,2),c=(4,1)(1)求满足a=mb+nc的实数m,n; (2)若(a+kc)垂直(2b-a),求实数k的值(3)若d满足(d-c)平行(a+b),d-c的绝对值=根号5,求d
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![平面内给定三个向量a=(3,2),b=(-1,2),c=(4,1)(1)求满足a=mb+nc的实数m,n; (2)若(a+kc)垂直(2b-a),求实数k的值(3)若d满足(d-c)平行(a+b),d-c的绝对值=根号5,求d](/uploads/image/z/2804411-11-1.jpg?t=%E5%B9%B3%E9%9D%A2%E5%86%85%E7%BB%99%E5%AE%9A%E4%B8%89%E4%B8%AA%E5%90%91%E9%87%8Fa%3D%283%2C2%29%2Cb%3D%28-1%2C2%29%2Cc%3D%284%2C1%29%281%29%E6%B1%82%E6%BB%A1%E8%B6%B3a%3Dmb%2Bnc%E7%9A%84%E5%AE%9E%E6%95%B0m%2Cn%3B+%282%29%E8%8B%A5%28a%2Bkc%29%E5%9E%82%E7%9B%B4%EF%BC%882b-a%29%2C%E6%B1%82%E5%AE%9E%E6%95%B0k%E7%9A%84%E5%80%BC%EF%BC%883%EF%BC%89%E8%8B%A5d%E6%BB%A1%E8%B6%B3%EF%BC%88d-c%29%E5%B9%B3%E8%A1%8C%EF%BC%88a%2Bb%29%2Cd-c%E7%9A%84%E7%BB%9D%E5%AF%B9%E5%80%BC%EF%BC%9D%E6%A0%B9%E5%8F%B75%2C%E6%B1%82d)
平面内给定三个向量a=(3,2),b=(-1,2),c=(4,1)(1)求满足a=mb+nc的实数m,n; (2)若(a+kc)垂直(2b-a),求实数k的值(3)若d满足(d-c)平行(a+b),d-c的绝对值=根号5,求d
平面内给定三个向量a=(3,2),b=(-1,2),c=(4,1)
(1)求满足a=mb+nc的实数m,n; (2)若(a+kc)垂直(2b-a),求实数k的值
(3)若d满足(d-c)平行(a+b),d-c的绝对值=根号5,求d
平面内给定三个向量a=(3,2),b=(-1,2),c=(4,1)(1)求满足a=mb+nc的实数m,n; (2)若(a+kc)垂直(2b-a),求实数k的值(3)若d满足(d-c)平行(a+b),d-c的绝对值=根号5,求d
(1)a=mb+nc
-m+4n=3
2m+n=2
解得n=8/9,m=5/9
(2)(a+kc)(2b-a)=2ab-a^2+2kbc-kac=2-13-4k-14k=0
k=-11/18
(3)(d-c)平行(a+b),设d=(x,y)则(4-x)/(1-y)=(3-1)/(2+2)=1/2,
(4-x)^2+(1-y)^2=5
解方程组得x=7/2,y=0,d=(7/2,0)
或x=9/2,y=2,d=(9/2,2)
笨蛋死吧
求满足a=mb+nc的实数m,n; (3,2)=m(-1,2)+n(4,1),3=-m+4n又2=2m+n解以上方程知m=5/9,n=8/9,
(1)a=mb+nc
-m+4n=3
2m+n=2
解得(1)a=mb+nc
-m+4n=3
2m+n=2
解得n=8/9,m=5/9
(2)(a+kc)(2b-a)=2ab-a^2+2kbc-kac=2-13-4k-14k=0
+++++7777777777777777777777777777777