Question

if 9th term of an Ap is zero prove that is 29 th term is double than its 50 th term

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Answer 1

Answer:

$\sf{\underline{\bold{solution}}}\\\\9th\:term=0\\\\\implies\:a+(9-1)d=0\\\\0r,a+8d=0\\\\\implies\:a=-8d........equ(1)\\\\30th\: term\:=a+29d=-8d+29d=21d\:\bigg[Using\:equation (1)\bigg]\\\\51th\:term=a+50d=-8d+50d=42d\\\\2\times21d=42\\\\2\times30th\term=51th\:term.$