Explain this to me i don't understand it.

find the perimeter of the triangle formed in the coordinate plane by the following points:

x (0 ,2)
y (3,-2)
z (-7,-2)

what i have is d=v (3-0)^2 + (3-7)^2

If f(x)= sqrt4x+9+2, which inequality can be used to find the domain of f(x)?

At $1.32 million, they closed last month percent above what they paid in 2007." how much did they pay in 2007?

John used linear combination to solve the system of equations shown. he did so by multiplying the first equation by -3 and the second equation by another number to eliminate the x-terms. what number did jonas multiply the second equation by? 4x-6y=23x+5y=11