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Mathematics 8 Online
OpenStudy (anonymous):

5 combination 2

Nnesha (nnesha):

|dw:1443467122442:dw| like this

Nnesha (nnesha):

?

Nnesha (nnesha):

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

OpenStudy (anonymous):

k one sec

OpenStudy (anonymous):

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

Nnesha (nnesha):

looks good

OpenStudy (anonymous):

\[\frac{ 120 }{ 6! }\]

Nnesha (nnesha):

how did you get 6! ?

Nnesha (nnesha):

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

OpenStudy (anonymous):

1*2(3)!

Nnesha (nnesha):

\[2(3)!=2(3 \times 2 \times 1)\]

OpenStudy (anonymous):

so 120/12

OpenStudy (anonymous):

=10

Nnesha (nnesha):

right

OpenStudy (anonymous):

thx

Nnesha (nnesha):

np,good work!

OpenStudy (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.

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