If →p=^i+^j+^k and →q=a^i+b^j+c^k where a,b,c→{−2,−1,0,1,2}. then the number of vectors →q is perpendicular to →a is
A
7
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
12
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
15
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
19
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution
The correct option is C19 →p.→q=(^i+^j+^k).(a^i+b^j+c^k) =a+b+c ⇒^i.^i=^j.^j=^k.^k=1 and ^i.^j=^j.^k=^k.^i=0 ⇒→p.→q=0 ⇒a+b+c=0 ⇒a=b=c=0, one vectora=0,b=1,c=−1,6 vectors by a,b,c a=0,b=2,c=−2,6 vectors a=b=1,c=−2,3 vectors a=b=−1,c=2,3 vectors these are 1+6+6+3+3=19 vectors