Question

The vectors î+ 29+ 3k, a î+ 49+7 K. - 3 i-2)-5k are collinear,
2 is equal to
a) 3
(b) 4
(c) 5
(d) 6​

Answer 1

Given,

i+2j+3k , ai+4j+7k , -3i-2j-5k are collinear

then delta=0

1 2 3

a 4 7 =0

-3 2 -5

1(-20-14)-2(-5a+21)+3(2a+12)=0

-34+10a-42+6a+36=0

16a=40

a=5/2