If $$y=2 x$$ is a chord of circle $$x^2+y^2-10 x=0$$, then the equation of circle with this chord as diameter is

If $$\sin ^2 x+\cos ^2 y=1$$, then $$\frac{d y}{d x}=$$

If $$f(x)=2\{x\}+5 x$$, where $$\{x\}$$ is fractional part function, then $$f(-1.4)$$ is

The curve $$y=a x^3+b x^2+c x+5$$ touches $$X$$-axis at $$P(-2,0)$$ and cuts $$Y$$-axis at a point $$Q$$, where its gradient is 3, then