√25
5√2
2√5
5√22
Correct answer is A
F=F1+F2
(2i−5j)+(−3i+4j)=(−i−j)
F=ma⟹(−1,−1)=5a
a=(−15,−15)
|a|=√(−15)2+(−15)2=√225
|a|=√25ms−2
Find the direction cosines of the vector 4i−3j.
910,2710
1727,−1727
45,−35
47,−37
Correct answer is C
Given V=xi+yj, the direction cosines are x|V|,y|V|.
|4i−3j|=√42+(−3)2=√25=5
Direction cosines = 45,−35.
If →OA=3i+4j and →OB=5i−6j where O is the origin and M is the midpoint of AB, find OM
-2i - 10j
-2i + 2j
4i - j
4i + j
Correct answer is C
→OA=(3,4)
→OB=(5,−6)
→OM=(3+52,4+(−6)2)
= (4,−1)=4i−j
Find the least value of n for which 3nC2>0,n∈R
13
16
23
1
Correct answer is C
3nC2>0⟹3n!(3n−2)!2!>0
3n(3n−1)(3n−2)!(3n−2)!2>0
3n(3n−1)2>0
3n(3n−1)>0⟹n>0;n>13
The least number in the option that satisfies n>0;n>13=23