Question

If a=(3,-1,-4), b=(-2,4,-3) and c=(-1,2,-5) then find magnitude of vector a+2b-c??​

Answer 1

Answer:

a can be written as $3 i -j-4k$

b can be written as $-2i+4j-3k$

c can be written as $-i+2j-5k$

Then a+2b-c must equal:

$3i-j-4k-4i+8j-6k-(-i+2j-5k)\\=-i+3j-10k + i-2j+5k\\=j-5k$

The magnitude of j-5k :

$\sqrt{1^{2} + 5^{2} } = \sqrt{26}$