Algebra 1

$t=15, -11$
$t^2-4t-165=0$ $t^2-4t-165+(4/2)^2=0+(4/2)^2$ $t^2-4t+4-165 = 4$ $(t-2)^2-165 =4$ $(t-2)^2-165+165 =4+165$ $(t-2)^2 = 169$ $\sqrt {t-2}^2 =\sqrt {169}$ $t-2 = 13$ or $t-2 = -13$ $t=15, -11$