Answer
$t=4$
Work Step by Step
$2t = \sqrt {2t +56}$
$(2t)^2 = (\sqrt {2t +56})^2$
$4t^2 = 2t+56$
$4t^2-2t-56 = 2t+56-2t-56$
$4t^2-2t-56 =0$
$(4t^2-2t-56 =0)/2$
$2t^2-t-28 =0$
$(2t+7)(t-4) = 0$
$2t+7=0$
$2t=-7$
$2t/2 = -7/2$
$t = -3.5$
$t-4=0$
$t=4$
$t = -3.5$
$2t = \sqrt {2t +56}$
$2*-3.5 = \sqrt {2*-3.5 +56}$
$-7 = \sqrt {-7 + 56}$ (we can't have a negative number as the square root of a number, so this answer is invalid)
