Question 1181925
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In the expansion of (2x+1)^n, the coefficient of the x^2 term is 40n , 
where n is a positive integer. Find the value of n.
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<pre>
The coefficient at x^2 is  {{{2^2*C[n]^2}}} = {{{4*(n*(n-1)/2)}}},


so we have this equation


    {{{4*(n*(n-1)/2)}}} = 40n,  or


    {{{((n-1)/2)}}} = 10

    n-1 = 20

    n = 21.        <U>ANSWER</U>
</pre>

Solved.