Tip:A–D to answerE for explanationV for videoS to reveal answer
If 2nC3:nC3=10:1, then the ratio (n2+3n):(n2−3n+4) is :
- A.
27:11
- B.
35:16
- C.
2:1
(Correct Answer) - D.
65:37
Explanation
nC32nC3=10⇒(2n−3)!n!(2n)!(n−3)!=10[∵nCr=r!(n−r)!n!]
⇒n−24(2n−1)=10⇒n=8
Now n2−3n+4n2+3n=64−24+464+24=12
Explanation
nC32nC3=10⇒(2n−3)!n!(2n)!(n−3)!=10[∵nCr=r!(n−r)!n!]
⇒n−24(2n−1)=10⇒n=8
Now n2−3n+4n2+3n=64−24+464+24=12
