Explain why it is important to line up decimal numbers by their place value when you add or subtract them

Me solve this problem, and someone clearly explain to me how to solve it.1.) use the value of the discriminant to determine if the given trinomials has 2 real solutions, 1 real solution, or no real solutions.a.  x2  − 4x  − 7 = 0b. 4r2  + 11r  − 3 = 0c. 3m2  + 7 = 0d.  t2  + 2t  + 1 = 0

Find the value. a. 0.003 b. 0.03 c. 0.3 d. 3

What is the radius of a circle with an area of 78.5 cubic inches? use 3.14 for pie