When is the the substitution method a better method than graphing for sloving a system of linear equations

1. what is the formula for finding the vertical distance between two points on a coordinate plane?

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?

Select all expressions that are equivalent to 2(3x + 7y). question 1 options: 6x + 14y 6x + 7y 1(6x + 14y)