Question

Помогите пожалуйста, не успеваю всё

Answer 1

1) $C^{12}_{14}=C^2_{14}= frac{14*13}{1*2} =7*13=91$
$C^{13}_{14}=C^1_{14}=14$
$C^{12}_{14}+C^{13}_{14}=91+14=105$

2) $C^8_{11}=C^3_{11}= frac{11*10*9}{1*2*3}=11*5*3=165$
$C^9_{11}=C^2_{11}= frac{11*10}{1*2}=11*5=55$
$C^{10}_{12}=C^2_{12}= frac{12*11}{1*2}=6*11=66$
$C^8_{11}+C^9_{11}+C^{10}_{12}=165+55+66=286$

3) $C^2_{35}= frac{35*34}{1*2} =35*17=595$
$C^2_{34}= frac{34*33}{1*2} =17*33=561$
$C^2_{35}-C^2_{34}=595-561=34$

4) $C^3_{26}= frac{26*25*24}{1*2*3}=26*25*4=2600$
$C^2_{25}= frac{25*24}{1*2}=25*12=300$
$C^3_{26}-C^2_{25}=2600-300=2300$