Question

a=(1,-2),b=(2,3),c=(1,1)将a表示成b1+c1的形式,其中b1//b,c1//c

Answer 1

因为 b1//b,c1//c,所以 可设

b1 = mb = m*(2,3) = (2m,3m)

c1 = nc = n*(1,1) = (n,n)

a = b1 + c1

(1,-2) = (2m,3m) + (n,n)

(1,-2) = (2m+n,3m+n)

1 = 2m + n

-2 = 3m + n

m = -3

n = 7

b1 = (-6,-9)

c1 = (7,7)

a = (1,-2) = (-6,-9) + (7,7)