Answer:

Step-by-step explanation:

usually if it comes to worse, we can always just use the product of all denominators as the LCD, it will just be a CD but not LCD but as good, but usually we try to use the LCD.
in this case our denominators do not have a GCF, so the LCD will just be their product, so we'll use that.
![\bf \cfrac{3x}{x-1}+\cfrac{4}{7x}\implies \stackrel{\textit{using an LCD of (x-1)(7x)}}{\cfrac{(7x)3x~~+~~(x-1)4}{(x-1)(7x)}}\implies \cfrac{21x^2~~+~~(4x-4)}{(x-1)(7x)} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill \cfrac{21x^2+4x-4}{(x-1)(7x)}~\hfill](https://tex.z-dn.net/?f=%5Cbf%20%5Ccfrac%7B3x%7D%7Bx-1%7D%2B%5Ccfrac%7B4%7D%7B7x%7D%5Cimplies%20%5Cstackrel%7B%5Ctextit%7Busing%20an%20LCD%20of%20%28x-1%29%287x%29%7D%7D%7B%5Ccfrac%7B%287x%293x~~%2B~~%28x-1%294%7D%7B%28x-1%29%287x%29%7D%7D%5Cimplies%20%5Ccfrac%7B21x%5E2~~%2B~~%284x-4%29%7D%7B%28x-1%29%287x%29%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20~%5Chfill%20%5Ccfrac%7B21x%5E2%2B4x-4%7D%7B%28x-1%29%287x%29%7D~%5Chfill)
1,333.166 square meters is the surface area.
Standard form is ax+by=c, where a and b and c are integers and a is normally posotive
some people say standard form is ax+by-c=0, so I'll put both forms
y=1/2x-5
mnus 1/2x both sides
-1/2x+y=-5
times -2 both sides
x-2y=10
other form
x-2y-10=0