Answer:
If f(1)=0 then 1 is a root and (x-1) is a factor of f(x). divide f(x) by (x-1). you now have a quadratic. Find its roots by methods you know.  
actually this factors by grouping:
f(x)=x³+3x²-x-3
= x²(x+3)-1(x+3)
=(x+3)(x²-1)
=(x+3)(x-1)(x+1) // difference of squares
By zero product property roots are
-3, -1, 1
 
        
             
        
        
        
ΔIJK ≈ ΔPQR => ∡I = ∡P =>
=> 3X + 4 = 72 - X
3X + X = 72 - 4
4X = 68
X = 68 : 4
X = 17
 
        
                    
             
        
        
        
Answer:
A single pencil costs $0.85 and a single eraser costs $0.60 
 
        
                    
             
        
        
        
Given the rate of water flow is given by:
r(t)=85e^(-0.04t)
thus the amount of water flow in the first hour when t=1, will be:
r(1)=85e^(-0.04*1)
=81.667
thus the amount of water that flowed out will be:
85-81.667
=3.333 liters