SOLUTION: If 15c3r = 15cr+3, then r = 1. 2 2. 3 3. 4 4. 5

Question 974074: If 15c3r = 15cr+3, then r =

1. 2
2. 3
3. 4
4. 5

Answer by farohw(175) (Show Source): You can put this solution on YOUR website!

Hello,

I remember this from Discrete Math.

15 is a superscript of C and 3r, r+3 are subscripts of C. If 15C3r = 15Cr+3, then we follow the formula:

nCx = nCy where x = y OR x + y = n.

Let n represent 15, x = 3r and y = r +3:

3r = r + 3 and 3r + r + 3 = 15

3r = r + 3 ---> 3r - r =3 then 2r = 3 which is r = 3/2

3r + r + 3 = 15 ---> 4r = 12 which is r = 3

r cannot be a fraction since this will give us 1.5 therefore the answer will be r = 3.

RELATED QUESTIONS
If (r+ (1/r))^2=5, then find the value of r^3 +... (answered by venugopalramana)

If (0.0001)^p = (0.1)^r then p is equal to the A r/4 B r/3 C r^2 �1 D... (answered by Fombitz)

Let r_1, r_2, r_3, r_4, and r_5 be the complex roots of x^5 - 4x^2 + 7x - 1 = 0. Compute (answered by CPhill,ikleyn)

If ... 1 + 2 = 32 3 + 4 = 712 Then ... 0+5 = ?? (answered by rapaljer)

4(x-2)=9(x+3)... (answered by ReadingBoosters)

3(r + 3) + 2(r -... (answered by lenny460)

Please describe and correct the error: (r^2-7r+12/r+4)/(r^2-7r+12/r^2+6r+8)=... (answered by jsmallt9)

Please describe and correct the error.

  {{{((r^2 -7r +12)/(r+4))  /  ((r^2... (answered by Edwin McCravy)