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January 30, 2015

January 30, 2015

Posted by **Lily** on Wednesday, February 25, 2009 at 8:47pm.

1 )3x + 8y = 1

7x + 4y = 17

Answer: (3,1)

2) -3x + 5y = -7

9x + 2y = 38

Answer: (4,1)

3) 7r + 3s = 13

14r - 15s = -16

Answer: (1,2)

4) 2x - 7y = 42

4x - 14y = 64

Answer: No Solution ??

5) 9x + 12y = 15

3x + 4y = 5

Answer: Identity ??

6) 2 = 4s - 3t

2 = 12s - 9t

Answer: No Solution ??

7) 3a - 6b = 18

4a + 8b = 24

Answer: (6,0)

If I got any of these wrong, can someone please show me the right way to do them?

These I have no idea on how to do them.

8) 4x +8y = 5

5x +10y = 13

9) 13 = 8a - 8b

6 = 4a - 5b

10) 160 = 2x - 10y

120 = 3x - 15y

Can anyone show me how to do these ones, I keep trying to solve them, but keep getting the wrong answer?

- 8th Grade Algebra- Answer Check -
**Reiny**, Wednesday, February 25, 2009 at 9:43pm#8 has no solution, here is why...

1st one times 5

20x + 40y = 25

2nd one times 4

20x + 40y = 52

subtract them

0 = 27 which is false

if it ever happens that the variables disappear and the remaining statement is false, there is no solution.

If the remaining statement would be true, such as in 0 = 0, there would be an infinite number of solutions.

#9.

1st one :

13 = 8a - 8b

2nd one times 2

12 = 8a - 10b

subtract the first equation minus the new second one

1 = 2b

b = 1/2

back in #1

13 = 8a - 4

17 = 8a

a = 17/8

check in original 2nd

LS = 6

RS = 4(17/8) - 5(1/2)

= 17/2 - 5/2

= 12/2 = 6 = LS

#10 is just like #8

see if you finish it yourself

- 8th Grade Algebra- Answer Check -
**jack**, Sunday, March 1, 2009 at 2:12pma times a + b times b =11 and a times b =3 what does a and b equals

- 8th Grade Algebra- Answer Check -
**rbi**, Monday, September 14, 2009 at 9:46pmtwo kinds of grouping symbols

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