1. what is the solution of the system
3x - y = 14,
4x + y = 21
a (-5,3)
b (4, -2)
c (5, 1)

The answer to your question is letter C

Step-by-step explanation:

Equations

                             3x  - y  = 14     (I)

                             4x + y =   21     (II)

Solve the system of equations by the elimination method.

                            3x -  y  = 14

                            4x + y  = 21

                            7x   0   = 35

Solve for x, divide both sides by 7

                                  7x/ 7 = 35/7                        

                                         x = 5

Substitute x in equation I

                            3(5) - y = 14

                            15 - y = 14

Subtract 15 in both sides

                            15 - 15 - y = 14 - 15

Simplify

                                      - y = -1

Multiply by -1

                                        y = 1

Solution

                                      (5, 1)                          

a4 - 3a2 - 1

step-by-step explanation:

step   1   :

equation at the end of step   1   :

  ((a4) -   3a2) -   1

step   2   :

trying to factor by splitting the middle term

2.1     factoring   a4-3a2-1  

the first term is,   a4   its coefficient is   1 .

the middle term is,   -3a2   its coefficient is   -3 .

the last term, "the constant", is   -1