1980 年

$2ab-a^2-b^2=$

$125^a\cdot 5^b=$

If $4p=9q$, then $\dfrac{4p^2}{9q^2}=$

If $n=10^a$, then $\log_{10}n=$

$\dfrac{x^{-2}-y^{-2}}{x^{-1}-y^{-1}}=$

If $\dfrac{1}{x}=a+b$ and $\dfrac{1}{y}=a-b$, then $x+y=$

If $x=\dfrac{y+(n-1)z}{n+1}$, then $n=$

$\dfrac{5^{n+2}-35(5^{n-1})}{18(5^{n+1})}=$

Solve the inequality $(4x+3)(x-4)>0$

When the hour hand has turned through an angle $x^\circ$, what is the angle through which the minute hand has turned?