Answer:
Step-by-step explanation:
utilise the Foil method to expand brackets:
F - mulply the first terms (x and x)
O - multiply the outside terms ( x and -2)
I - multiply the inside terms (5 and x)
L - multiply the last terms (5 and -2)
Then add them as following:
Then combine like terms:
check the picture below, that's pretty much the same block, or "rectangular prism", with a width of 10, length of 5 and height of 1.
so anyhow, is really 6 rectangles stacked up to each other at the edges, so, we can simply get the area of each of those rectangles, add them up and that's the surface area.
front and back, two rectangles of 5x1
left and right, two rectangles of 1x10
top and bottom, two rectangles of 10x5
