1999 年

If $\mathrm{f}(x)=x^2-1$, then $\mathrm{f}(a-1)=$

$x^2-y^2-x+y=$

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

If $4^x=a$, then $16^x=$

In the figure, the graph of $y=x^2-6x+k$ touches the $x$-axis. Find $k$.

If $(3x-1)(x-a)\equiv 3x^2+bx-2$, then

Solve $x^2+10x-24>0$.

If $\begin{cases} y=x^2+3x-2 \\ y=-x+3 \end{cases}$, then

Which of the following may represent the graph of $y=x^2-3x-18$ ?

The $n$-th term of an arithmetic sequence is $2+5n$. Find the sum of the first $100$ terms of the sequence.