Question

Lesson 3 Unit 7, Solving Systems Using Elimination Quiz

1. (I'VE ALREADY ANSWERED THIS)

2. What is the solution of the system?

7x + 5y = 19
-7x - 2y = -16

(A). (2, 1)
(B). (1, 2)
(C). (7, 5)
(D). (-7, -2)

3. Which method would be the simplest way to slove the system?

y = 1/2x
2x + 3y = 28

(A). Graphing
(B). Substitution
(C). Elimination
(D). Distributive

4. What is the solution of the system?

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

(A). (2, 6)
(B). (-1, 3)
(C). (-2, 6)
(D). (1.5, -4.5)

5. How many solutions does this system have?

-3x + 6y = 10
-3x + 6y = -4

(A). None
(B). One
(C). Infinite
(D). Two

6. In wich quadrant does the solution of the system fall?

y = x - 1
y = -3x - 5

(A). I
(B). II
(C). III
(D). IV

Answer 1

Answer:

2) A

3) B

4) C

5) A

6) C

Step-by-step explanation:

2) Lets add 2 equation together, we will find:

$7x-7x+5y-2y=19-16\\3y=3\\y=1$

If we put y value in the first equation:

$7x+5=19\\7x=14\\x=2$

It is A

3) Substation is the best way to solve the system.

Lets multiply first equation with 4:

$4y=2x$

Substitute 2x with 4y:

$4y+3y=28\\y=4$

and x=8

4) Again lets substitute 3x with -y:

$-y+2y=6\\y=6$

Therefore x=-2

Correct answer is C

5) None of real numbers is the solution of this system.

6) First lets multiply first equation with -1 and add equations together:

$y-y=-3x-x-5+1\\0=-4x-4\\x=-1\\y=-2$

It falls to III

The answer is C