Question

If a(0,-1,3)+b(1,1,1)-c(1,2,5)=(-2,3,-8), determine a,b,c

Answer 1

I am assuming that a , b , and c are scalars and this is scalar multiplication , if so, then
b - c = -2
-a + b -2c = 3
3a + b - 5c = -8

you got 3 equations in 3 unknowns, should be easy
I will start you off....
subtract the first two
a+c=-5

subtract the last two
-4a + 3c = 11

take it from there