Solving Lesson 11 Page 39 Math Study Topic 10 – Kite>


Topic

A group of 10 students participated in the Green Summer campaign. The school wants to select a task force with at least two of these students. How many ways are there to set up such a team?

Solution method – See details

Write the general formula and use Newton’s binomial to reduce the expression

Detailed explanation

+ Number of ways to choose 2 students out of 10: \(C_{10}^2\)

+ Number of ways to choose 3 students out of 10: \(C_{10}^3\)

+ Number of ways to choose 10 students out of 10 students: \(C_{10}^{10}\)

=> The number of ways to choose is:

\(\begin{array}{l}C_{10}^2 + C_{10}^3 + C_{10}^4 + … + C_{10}^{10} = \left( {C_{10} ^0 + C_{10}^1 + C_{10}^2 + … + C_{10}^{10}} \right) – \left( {C_{10}^0 + C_{10}^1} \right)\\ = {2^{10}} – 1 – 10 = {2^{10}} – 11\end{array}\)



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