Question

If you answer ALL questions listed, you get a good amount of points (3 questions, 5 points each, 15 points total) :D

1) Which pair are solutions to the equation?

4xy + 8 = 36

A.
(7, 1) and (3, 2)

B.
(1, 7) and (7, 1)

C.
(1, 7) and (4, 9)

D.
(4, 9) and (3, 2)

2)
Which of the ordered pairs in the form (x, y) is a solution of this equation?

5x - y over 3 = 13,
(2, -9) (3, -6)

A.
The first is not a solution, but the second is.

B.

Both are solutions.

C.

The first is a solution, but the second is not.

D.

Neither is a solution.

3)
Which ordered pairs in the form (x, y) are solutions to the equation

7x – 5y = 28?



Choose all answers that are correct.

A.

(−6, −14)

B.

(−1, −7)

C.

(4, 10)

D.

(7, 9

Answer 1

1)

$4xy+8=36\\4xy=28\\xy=7$

We know that each coordinate (x,y) must therefore multiply to equal 7. The only numbers that multiply to 7 are 7 and 1, so B) is the correct answer.



2)

For this one, just plug in the coordinates they give you for x and y and see if either one works:

$5x-\frac{y}{3}=13\ \ \ \ \ \ \ (2,-9)\\5(2)-\frac{(-9)}{3}=13\\10-(-3)=13\\13=13$

So the first one is a solution. Now plug in the second one:

$5x-\frac{y}{3}=13\ \ \ \ \ \ (3,-6)\\5(3)-\frac{(-6)}{3}=13\\15-(-2)=13\\17=13$

Therefore, the first is a solution and the second isn't making C) the correct answer.



3)

For this one, just plug in the ordered pairs they give you and see which ones end up working:

$7x-5y=28\\\\A. (-6,-14)\\7(-6)-5(-14)=28\\-42+70=28\\28=28\\\\B.(-1,-7)\\7(-1)-5(-7)=28\\-7+35=28\\28=28\\\\C.(4,10)\\7(4)-5(10)=28\\28-50=28\\-22=28\\\\D.(7,9)\\7(7)-5(9)=28\\49-45=28\\4=28$

A) and B) are the only ones that work out, so those are the correct answers.

Answer 2

1.  4xy+8=36

   4xy=28

   xy=7

2. 5(2)-(-9)/3=13

    10-(-3)=13

     13=13

     5(3)-(-6)/3=13

     15-(-2)=13

     17≠13

3. 7(-6)-5(-14)=28

   -42+70=28

     28=28

    7(-1)-5(-7)=28

    -7+35=28

      28=28

     

   7(4)-5(19)=28

   28-50=28

    -22≠28

  7(7)-5(9)=28

  49-45=28

    4≠28

Hope this helps... :)