Find the value of n such that x2-10x+n is a perfect square trinomial. a. -5 b. 50 c. 100 d. 25

The answer is the last option (Option D), which is:

 D. 25

 The explanation is shown below:

 1. You have that:

 (a ± b)^2=a^2 ± 2ab + b^2

 2. The expression given in the problem is:

 x^2-10x+n

 Where x^2=a and 2ab=10x

 2b=10
 b=10/2
 b=5

 3. Therefore, you have:

 b^2=5
 b^2=25

 b^2=n
 n=25

Volume of the sphere = (4/3) * 3.14 *  (2.35)^3       [ 2.35 = 1/2 * 4.7 = radius]

total weight = vol * density  = (4/3) * 3.14 * 2.35^3  * 14.25 

                    =  774.26 pounds