## anonymous one year ago 5 combination 2

1. Nnesha

|dw:1443467122442:dw| like this

2. Nnesha

?

3. Nnesha

if yes then use the formula $\huge\rm ^nC_r= \frac{ n! }{ r!(n-r)! }$

4. anonymous

k one sec

5. anonymous

$\frac{ 5! }{ 2! (5-2)! }=\frac{ 1*2*3*4*5 }{ 1*2(3)! }$

6. Nnesha

looks good

7. anonymous

$\frac{ 120 }{ 6! }$

8. Nnesha

how did you get 6! ?

9. Nnesha

you can't multiply 2 with 3! 3! is 3 times 2 times1 so 1 times 2 (3 times 2)

10. anonymous

1*2(3)!

11. Nnesha

$2(3)!=2(3 \times 2 \times 1)$

12. anonymous

so 120/12

13. anonymous

=10

14. Nnesha

right

15. anonymous

thx

16. Nnesha

np,good work!

17. phi

btw, it is better to do it this way: $\frac{5\cdot 4 \cdot 3!}{2 \cdot 3!}$ notice that the 3! cancels, you have have 5* 4/2 = 5*2 =10 this way you don't have to calculate huge numbers.