If $m_1$ and $m_2$ are the slopes of the lines represented by $a x^2+2 h x y+b y^2=0$ satisfying the condition $16 \mathrm{~h}^2=25 \mathrm{ab}$, then ............ .

The modulus of the square root of the conjugate of $-7+24 \sqrt{-1}$ is __________

If $x+\log _{15}\left(5+3^x\right)=x \log _{15} 5+\log _{15} 24, \quad$ then $x=$ _________

If $\mathrm{f}(x)$ is continuous at point $x=0$ where $$ f(x)=\left\{\begin{array}{cc} \frac{3 \sin x+5 \tan x}{\mathrm{a}^x-1} & , x<0 \\ \frac{2}{\log 2} & , x=0 \\ \frac{8 x+2 x \cos x}{\mathrm{~b}^x-1} & , x>0 \end{array}\right. $$ then the values of a and b , respectively, are __________