Question

Help Please !!

Choose the equivalent system of linear equations that will produce the same solution as the one given below.

4x - 2y = 6
2x + y = 5

-4x - 2y = 10
-4y = 4

-4x - 5y = -1
-7y = 5

3x + 2y = 6
7x = 12

4x + 2y = 10
8x = 16

Answer 1

anyobdy there ??

Answer 2

This looks like it takes time.
I would solve the system they "gave" as a first step.

can you do that ?

Answer 3

i dont know how to @phi

Answer 4

4x - 2y = 6
2x + y = 5

multiply the second equation by 2. (that means *all* terms, on both sides by 2)
can you do that ?

Answer 5

which would be 4x + 2x = 5

Answer 6

almost. that second term should be 2y (right?)
and when we double the left side we have to double the right side to keep it an equation

in other words, don't forget the 5
try again.

Answer 7

ok so 4x + 2y = 10

Answer 8

4x - 2y = 6
4x + 2y = 10

now add the two equations. which just means write them as
4x+4x -2y +2y = 6+16

can you simplify that ?

Answer 9

hold on let me try

Answer 10

**4x+4x -2y +2y = 6+10

Answer 11

8x - y = 16

Answer 12

ok, except -2y + 2y is not -y

2 y's take away 2 y's is how many y's ?

Answer 13

it would be 0

Answer 14

yes, and
4x+4x -2y +2y = 6+10

simplifies to
8x= 16

now divide both sides by 8

Answer 15

2 ?

Answer 16

you should write both sides
8x/8 = 16/8
on the left side 8/8 * x is 1*x = x
on the right side 16/8 is 2
we get
x=2

Answer 17

so it would be D ?

Answer 18

this is a painful question.

so far we know x=2
use one of the two equations they gave us
example
2x + y = 5 (I picked this because it has smaller numbers, but the other works also)

replace x with 2
2*2 + y =5

can you "solve" for y?
I would simplify 2*2 to 4
then add -4 to both sides

Answer 19

Dang.. i dont know how to do all that i figured it would be B since we got 8x= 16

Answer 20

you do it like lots of things. 1 step at a time
2x + y = 5

we figured out x=2
replace x with 2:

2*2 + y = 5

what is 2*2 ?

Answer 21

4

Answer 22

ok.

2*2 + y = 5
becomes
4+ y = 5

to "get rid" of the 4, add -4 (to both sides to keep it an equation)
4-4 + y = 5 - 4
simplify

Answer 23

y=1

Answer 24

ok, the "solution" to the given system is x=2, y=1

we need to try those numbers in the choices and see if they work for one of the choices (they better work for one of them)

Let's test the first choice:
-4x - 2y = 10
-4y = 4

the second equation is easier to test. if we replace y with 1 we get
-4*1 =? -4
-4 =? 4 .... Nope , that is not right. First choice is not the answer.

Answer 25

Ohh its b

Answer 26

can you test

-4x - 5y = -1
-7y = 5

test the second equation with y=1. does it work?

Answer 27

yes

Answer 28

can you show how you did it?

Answer 29

ohh no im not saying its b it was a typo i was trying to say a -4y=4

Answer 30

yes, but when you try y=1 you get -4*1 =4
and -4*1 is -4
and
-4 does not equal 4

It does not work.

Answer 31

omg im geting frustrated w/ this

Answer 32

It's a painful problem. But it's doable.

Do you follow how we tested
-4y= 4
to see if it's true if y is 1 ? we found it did NOT work.

Answer 33

yes sp im guessing its 7x=12 (c)

Answer 34

so*

Answer 35

no need to guess. remember x=2 is the solution for our system
does x=2 work for
7x=12 ?

Answer 36

ugh no it doesnt :(

Answer 37

that's good. we can cross of that choice.

Answer 38

okay and we can also cross out a right ?

Answer 39

test the last one

4x + 2y = 10
8x = 16

use the last equation . Does it work for x=2 ?

Answer 40

yes thats what i said the first time it was D

Answer 41

ok.
but the first equation has to also work.
4x+2y must equal 10
when we use x=2 and y=1
does it ?

Answer 42

no

Answer 43

4*2 +2*1

first do the multiplies
then add

Answer 44

8 + 3 = 11

Answer 45

2*1 is different from 2+1

Answer 46

ohh im sorry it equals 10

Answer 47

yes, so choice D is the answer.

A tough question (lots of work)

Answer 48

omg thank you so much !

Answer 49

yw