Answer: y= (x+2)² −
5
Step-by-step explanation:
The way I got this answer is by completing the square. The first step though, when looking at this equation, is to see if we can factor it. The way to check is to look at the coefficient for x² which is 1, and the constant, in this case -1. If we multiply those together, we get −. Now we look at the middle term, 4x. We need to find any numbers that multiply to equal − 1x² and add to 4x. There aren't any, which means it is not factorable.
Hope I helped
From the expression, the price is directly proportional to the boxes with k being the constant. therefore he bought 4 boxes for 25.6 having the initial constant to be 6.4
if he bought 10 boxes having a constant of 6.4 it becomes y=6.4*10 which becomes 64.
10π=2πr
Divide both sides by 2π
10π/2π=r
Simplify
5=r

where x is the estimated value and xr the real value

the percent error is 10.71%