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Let `f:R to R` be a differentiable function with `f(0)=0`. If `y=f(x)` satisfies the differential equation `(dy)/(dx)=(2+5y)(5y-2)`, then the value of `lim_(x to oo) f(x)` is………………. |
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Answer» Correct Answer - D `(dy)/(dx) = (5y+2)(5y-2)` `rArr 1/25int(dy)/(y^(2)-(2/5)^(2))=intdx` `=1/25.5/4log_(e)|(y-2)/(y+2/5)|=x+c` `=1/20 log_(e)|(5y-2)/(5y+2)|=x+c` Given that `f(0)=y(0)=0`. `therefore c=0` Hence, `|(2-5y)/(2+5y)|=e^(20x)` `therefore lim_(x to infty) |(2-5y)/(2+5y)|=lim_(x to -infty)e^(20x)` `rArr lim_(x to -infty)|(2-5y)/(2+5y)|=0` `lim_(x to -infty)y=2/5=0.4` |
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