Question

Using E= mc2 , solve for m. Then, find the value of m if E = 725 and c= -5

Answer 1

`E=mc^2\ \ \ \ |:c^2\\\\m=(E)/(c^2)\\\\m=(725)/((-5)^2)\\\\m=(725)/(25)\\\\\boxed{m=29}`

Answer 2

Divide by c^2, m=E/(c^2)
M=725/(-5)^2
M=725/25
M=29