Question

Dados os vetores a = (1,2,1) e b = (2,1,0), calcular 2aX (a+b)

Answer 1

A) 2a x (a + b) se for produto vetorial  

2a =(2,4,2)  

(a + b)=(3,3,1)  

A) 2a x (a + b)=  

i j k  

2 4 2  

3 3 1  

i(4-6)-j(2-6)+k(6-12)=  

-2i+4j-6k=(-2,4,-6)  

B) (a + 2b) x (a - 2b)  

a=(1,2,1) e b=(2,1,0), 2b=(4,2,0)  

(a + 2b) = (5,4,1)  

(a - 2b)=(-3,0, 1)  

Prod vetorial  

i j k  

5 4 1  

-3 0 1  

i(4-0)-(5+3)j+12k  

4i-8j+12k=(4,-8,12)