Vector a=(-1,3), b=(2, m), and a vertical (a-b) (1) Fact the value of m (2) When ka-b is parallel to a+b, fact the value of k

Vector a=(-1,3), b=(2, m), and a vertical (a-b) (1) Fact the value of m (2) When ka-b is parallel to a+b, fact the value of k

1) A-b=(-3,3-m) a⊥(a-b) so (-1,3)·(-3,3-m)=0 i.e.3+9-3m=0 so m=4
2) Kab=(-k-2,3k-4) a+b=(1,7)(ka-b)//(a+b) so7(-k-2)=3k-4 sok=-1

Given the vector a=(1,1), b=(-1, k), and a is perpendicular to b Find a*(a+b)

Given vector a=(1,1), b=(-1, k), and a is perpendicular to b
Then a*b=0
So a*(a+b)=a2+a*b=|a|2+0=1 2+12=2

Given the vector a=(1,1), b=(-1, k), and a is perpendicular to b
Then a*b=0
So a*(a+b)=a2+a*b=|a|2+0=1 2+12=2

Given a=(2,-1,1), b=(-1,1,-2), c=(3,2, x), if a, b, c are coplanar, then x is equal to?

A =(2,-1,1), b =(-1,1,-2), c =(3,2, x)
If a, b, c are coplanar, then there exists, m, n∈R such that
C=ma+nb
(3,2, X)= m (2,-1,1)+ n (-1,1,-2)=(2m-n,-m+n, m-2n)
{2M-n=3 1-m+n=2 2 x=m-2n3
Solve 12 to get: m=5, n=7 substituted into 3
X=-9

The following numbers are the four numbers on the 24-point playing card. Please choose the addition, subtraction, multiplication and division of parentheses to form the equation. 1.4、7、7 The following group of numbers are the four numbers on the 24-point playing card. Please choose the addition, subtraction, multiplication and division of parentheses to form the equation. 1.4、7、7

(7-4)*(7+1)

Multiply by and divide by 5 6 7 8 Four-number composition 24 Multiply by and divide by 5 6 7 8 Four-count composition 24

(7-5)×8+6=24
(7+5)×(8-6)=24
(5+7-8)×6=24
8×6÷(7-5)=24

0

(9-7)*5+4=24.
10+8*(7/4)=24.