Unit 5 Online Self Quiz

Click  for True  and    for False.

1. The number of points of intersection of the following graphs is three:

x2+ y2= 2

2x + y = 10  

           

2. When solving this system graphically, the graphs are a line and a parabola.

x2 + 2y = -6
x - y = 3

          

3.  Given:  

x + 2y = 9
3x - 2y= -5

If the elimination method is used to solve the system, the next step would be:

                x = -2y +9

             

4. If the total cost of running a business is given by the equation

C = 4.16x + 75,000
    and the revenue is given by the equation
R = 7.91x
,
find the sales necessary to break even.

x = 20,000  

       

5. Solve the linear system by the method of elimination:

 7x - 3y = 2
 2x + 5y = 25

        x = 3, y = 5  

       

6. Find the value of y in the solution of the system of equations:

 3x + 7y = 15
-5x + 2y = 16

  y = -2      

       

7. Suppose the demand and supply equations for a certain product are given by

p = 860 - 0.05x         Demand equation

p = 420 + 0.15x       Supply equation

then the  equilibrium value is 420 units.

                   

8. Use the method of back substitution to find the value of x for the solution of the system of equations.

  x + 2y + z = 15
       5y - 2z = -16
                z  = 3

      The solution for x is   x = 22    

      

9) Is (-1, 2, -2) the solution to the following the system of linear equations? Hint: store x,y and z in th graphics calculator. Ex  2 STO Alpha Y  

 x - 3y + 2z   = -11
x  + 4y  - 5z  = 17
-2x + y -  z    = 6


     

10) The system:

 x  +  3y = 9
2x + 6y  = 32
     has no solution.