Category: Permutation and Combination

Question Number 25928 by 786786AM last updated on 16/Dec/17 $$\mathrm{Expand}{(1-\mathrm{x})}^4.\mathrm{H}\mathbf{ence},\mathbf{find}\mathbf{S}\mathbf{if}\mathbf{S}={(1-{\mathrm{x}}^3)}^4-4{(1-{\mathrm{x}}^3)}^3+6{(1-{\mathrm{x}}^3)}^2-4{(1-{\mathrm{x}}^3)}^{}+1.$$ Terms of Service Privacy…

Question Number 91230 by waseemyaqoobese@gmail.com last updated on 28/Apr/20 $$\underset{j=o}{\sum ^m}\stackrel{a}{}{C}_j\stackrel{b}{}{C}_{m-j}=\stackrel{a+b}{}{C}_m$$$$solvethisproblem$$ Answered by ~blr237~ last…

Question Number 25237 by Mr eaay last updated on 06/Dec/17 $$prooovethat0!=1$$ Commented by prakash jain last updated on 07/Dec/17 $$\mathrm{It}\mathrm{is}\mathrm{a}\mathrm{notation}\mathrm{simplication}$$$$\mathrm{that}\:\mathrm{defines}\:\mathrm{empty}\:\mathrm{products} \…

Question Number 90503 by john santu last updated on 24/Apr/20 Commented by john santu last updated on 24/Apr/20 $$atotalof20marble$$ Commented by jagoll last…

Question Number 155816 by cortano last updated on 05/Oct/21 $$\mathrm{How}\mathrm{many}\mathrm{of}\mathrm{the}\mathrm{number}\mathrm{formed}$$$$\mathrm{by}\mathrm{using}\mathrm{all}\mathrm{the}\mathrm{digits}1,2,3,4,5,6$$$$\mathrm{only}\mathrm{once}\mathrm{divisible}\mathrm{by}25.$$ Answered by talminator2856791 last updated on 05/Oct/21 $$\:\mathrm{4}!\:=\:\mathrm{24} \…