Hello,
Maybe I'm mistaking... but if x=6, then is not defined.
Same thing for x=11.
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If x=2
then
And
So the expression is 2.
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Therefore, x=-2 ??
At what the term in the expansion of the binomial:
is equal to 21 if it is known that the binomial coefficients of the and the terms in the expansion represent respectively the first, third and fifth terms of an arithmetic progression?
(A)
(B)
(C)
(D)