I3.1 If $998 a+1=999^{2}$, find $a$.
I3.2 If $\log _{10} a=\log _{2} b$, find $b$.
I3.3 The area of the triangle formed by the $x$-axis, the $y$-axis and the line $2 x+y=b$ is $c$ sq. units. Find $c$.

I3.4 If $64 t^{2}+c t+d$ is a perfect square, find $d$.
$\begin{array}{l}998 a=999^{2}-1 \\ =(999-1)(999+1) \\ =998 \times 1000 \\ a=1000 \\ \log _{10} 1000=\log _{2} b \\ \log _{2} b=3 \\ \Rightarrow b=2^{3}=8 \\ 2 x+y=8 ; x \text {-intercept }=4, y \text {-intercept }=8 \\ c=\text { area }=\frac{1}{2} \cdot 4 \times 8=16 \\ 64 t^{2}+16 t+d \text { has a double root } \\ \Delta=16^{2}-4 \times 64 d=0 \\ d=1 \\\end{array}$