From the calculation above, Dave may have jumped the expression
[tex](x+4)^2= 144[/tex]
Given the expression solved by Dave from step 1 as;
[tex]\dfrac{1}{3}(x+4)^2&=48[/tex]
In order to determine what Dave would have written, we will solve the expression above as shown
[tex]\dfrac{1}{3}(x+4)^2&=48\\(x+4)^2 = 3*48\\(x+4)^2 = 144 ..............eqn \ 2\\[/tex]
Take the square root of both sides
[tex]\sqrt{(x+4)^2} =\pm\sqrt{144}\\x+4=\pm12[/tex]
Hence from the calculation above, Dave may have jumped the expression in equation 2 as shown below;
[tex](x+4)^2= 144[/tex]
Learn more on radical equations here: https://brainly.com/question/20931859