$t=37.5$

$t=\pm 5$

$p=16$

$x=\pm 4$

$x=7$ of $x=3$

$a=7$

$v=0.03$

there are no solutions because $\sqrt{(-4)}$ is not a real number

$x=4$

$x=1\vee x\approx 1.35$

-

$140$ m³ costs € 283 per year and $160$ m³ costs € 318, therefore between € 283 and € 318.

$38+1.75a=250$ gives $a\approx 121.143$ therefore a maximum of $121$ m³.

$p=0$ gives $q=-200$
$q=0$ gives $p=300$

$q=0$ gives $W=0$
$W=0$ gives $q=0$ of $q=200$

$l=0$ gives $k=\pm \sqrt{\left(96\right)}\approx \pm 9.80$
$k=0$ gives $l=8$ of $l=-12$

$d=0$ gives $a=20$
$a=0$ does not lead to any value for $d$

$V=200\pi {(1.5+0.5a)}^2-450\pi$

Y1=200π(1.5+0.5a)^2-450π with window settings $0\le x\le 1000$ and $0\le y\le 160000000$

Approximately $23$ dips