JEE MAIN - Mathematics (2019 - 12th January Evening Slot - No. 8)
The total number of irrational terms in the binomial expansion of (71/5 – 31/10)60 is :
54
55
49
48
Explanation
General term Tr+1 = 60Cr, $${7^{{{60 - r} \over 5}}}{3^{{r \over {10}}}}$$
$$ \therefore $$ for rational term, r = 0, 10, 20, 30, 40, 50, 60
$$ \Rightarrow $$ no of rational terms = 7
$$ \therefore $$ number of irrational terms = 54
$$ \therefore $$ for rational term, r = 0, 10, 20, 30, 40, 50, 60
$$ \Rightarrow $$ no of rational terms = 7
$$ \therefore $$ number of irrational terms = 54
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