1.

यदि `x=a cot theta + b sin theta, y=a sin theta cos, theta,` तो दर्शाइए कि `y^(2)""(d^(2)y)/(dx^(2))-x""(dy)/(dx)+y=0`.

Answer» `x=a cos theta + b sin theta `
`rArr (dx)/(d theta)=-a sin theta + b cos theta = - y ` ...(1)
`y=a sin theta - b cos theta`
`rArr (dy)/(d theta)=a cos theta + b sin theta x ` ...(2)
`:. (dy)/(dx)=(dy//d theta)/(dx // d theta)= - (x)/(y)` [समीकरण (1 ) व (2 ) से ]
`rArr y (dy)/(dx)+x=0`
x के सापेक्ष पुनः अवकलन करने पर,
`y(d^(2)y)/(dx^(2))+((dy)/(dx))^(2)+1=0`
`y^(2)(d^(2)y)/(dx^(2))+y(dy)/(dx)+y=0`
`rArr y^(2)(d^(2)y)/(dx^(2))-x(dy)/(dx)+y=0` [समीकरण (3 ) से ] (यही दिखाना था । )


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