Question

Solve the system using elimination.

3x – y = 28
3x + y = 14

Answer 1

(8, –4)
(–7, 7)
(7, –7)
(–4, 8)

Answer 2

hint: add the two equations together

Answer 3

start with the x's

3x + 3x = ?

Answer 4

3+3=6 28+14=42

Answer 5

almost

3 + 3 = 6
3x + 3x = ___

fill in the blank

Answer 6

6x?

Answer 7

good!

now go to the y's

-y + y = ?

Answer 8

0?

Answer 9

good!

now we have

6x = 42

x = ___

fill in the blank

Answer 10

do i add those together?

Answer 11

nope, just find x

Answer 12

6x = 42

what does x = ?

Answer 13

7

Answer 14

good! x = 7, so we look for the answer choice with an x-coordinate of 7

the only possibility is (7,-7)

Answer 15

yeah

Answer 16

can u help me with -5x+y=-5
-4x+2y=2

Answer 17

hint: multiply the first equation by 2 first

Answer 18

ok 10

Answer 19

nope

-5x*2 = ?

Answer 20

-10?

Answer 21

don't forget the x

Answer 22

ok, the way I wrote it was a bit vague, but I meant

(-5)*(2)*x = ?

Answer 23

-10x

Answer 24

what do I do next?

Answer 25

2*y = ?

Answer 26

whats y?

Answer 27

-5x + y = -5 ----multiply by -2
-4x + 2y = 2
------------
10x - 2y = 10 (result of multiplying by -2)
-4x + 2y = 2
------------add
6x = 12 -- divide by 6 on both sides
x = 2

now sub 2 in for x in one of the original equations and find y.
questions ?

Answer 28

-6?

Answer 29

-4*2+2=-6

Answer 30

-5x + y = -5
-5(2) + y = -5
-10 + y = -5
y = -5 + 10
y = 5

check...
-4x + 2y = 2
-4(2) + 2(5) = 2
-8 + 10 = 2
2 = 2 (correct)

so x = 2 and y = 5

Answer 31

someone told me 2,5 wasnt the right answer..

Answer 32

plug it into the original equations to check...
-4x + 2y = 2 -5x + y = -5
-4(2) + 2(5) = 2 -5(2) + 5 = -5
-8 + 10 = 2 -10 + 5 = -5
2 = 2 (correct) 5 = 5 (correct)

(2,5) is the solution because it checks out in both equations as correct

Answer 33

Thank You