For the first question, simply plug in the value of 3 into the polynomial question. The final answer is your volume of the hot water tub. 
For the second question, you can figure out that x = -5 is not a real root because it does not touch or cross the x axis. 
If it does it would be an solution. 
        
             
        
        
        
1. A
2. should be 42?
3.???
4.27 apples left
5.B 1/4
        
             
        
        
        
A is the correct answer.
The first term is, <span> <span>z2</span> </span> its coefficient is <span> 1 </span>.
The middle term is, <span> +z </span> its coefficient is <span> 1 </span>.
The last term, "the constant", is <span> -2 </span>
Step-1 : Multiply the coefficient of the first term by the constant <span> <span> 1</span> • -2 = -2</span> 
Step-2 : Find two factors of  -2  whose sum equals the coefficient of the middle term, which is  <span> 1 </span>.
<span><span>     -2   +   1   =   -1</span><span>     -1   +   2   =   1   That's it</span></span>
Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -1  and  2 
                     <span>z2 - 1z</span> + 2z - 2
Step-4 : Add up the first 2 terms, pulling out like factors :
                    z • (z-1)
              Add up the last 2 terms, pulling out common factors :
                    2 • (z-1)
Step-5 : Add up the four terms of step 4 :
                    (z+2)  •  (z-1)
             Which is the desired factorization
<span>Equation at the end of step  3  :</span><span> 3 • (z + 2) • (z - 1) = 0 </span>