Question

If 5. ⁴pᵣ = 6. ⁵pᵣ₋₁ then value(s) of 'r'

Answer 1

Step-by-step explanation:

5(4!)= 6×5!

(4-r)! (6-r)!

5×4! =6×5×4!

(4-r)! (6-r)(5-r)(4-r)!

(6-r)(5-r)=6

30-11r+r²=6

r²-11r+24=0

r²-8r-3r+24=0

r(r-8)-3(r-8)=0

(r-3)(r-8)=0

r=3 or 8