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If `S_(0),S_(1),S_(2),…` are areas bounded by the x-axis and half-wave of the curve `y=sin pi sqrt(x)," then prove that "S_(0),S_(1),S_(2),…` are in A.P… |
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Answer» `y= sin pi sqrt(x)` meets x-axis when `pisqrt(x)=npi or x=n^(2), n in N.` Therefore, area of half-wave between `x=n^(2) and x=(n+1)^(2)` is `S_(n)=|overset((n+1)^(2))underset(n^(2))int sin pi sqrt(x)dx |` `"Putting "pisqrt(x)=y and pi^(2) dx =2y dy,`we get `therefore" "S_(n)=|(2)/(pi^(2))overset((n+1)pi)underset(npi)inty sin y dy |` `=|(2)/(pi^(2))[-y cos y + sin y ]_(npi)^((n+1)pi)|` `=|(2)/(pi^(2))[-(n+1)pi cos (n+1) pi +npi cos n pi ]|` `=(2(2n+1))/(pi), n in N` `"Hence, "S_(0),S_(1),S_(2),...` are in A.P.. |
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